diff --git a/frontend/src/app/dashboard/glossaries/[id]/page.tsx b/frontend/src/app/dashboard/glossaries/[id]/page.tsx
index 20416ac..a1bbd01 100644
--- a/frontend/src/app/dashboard/glossaries/[id]/page.tsx
+++ b/frontend/src/app/dashboard/glossaries/[id]/page.tsx
@@ -363,18 +363,17 @@ export default function GlossaryDetailPage() {
             <label className="text-[10px] font-bold uppercase tracking-widest text-brand-dark/50 dark:text-white/50 mb-1.5 block">
               {t('glossaries.detail.sourceLang') || 'Langue source'}
             </label>
-            <select
-              value={sourceLanguage}
-              onChange={(e) => setSourceLanguage(e.target.value)}
-              disabled={isUpdating}
-              className="w-full h-10 rounded-lg border border-input bg-background px-3 text-sm focus:outline-none focus:ring-2 focus:ring-brand-accent/20"
-            >
-              {SUPPORTED_LANGUAGES.filter((l) => l.code !== 'multi').map((l) => (
-                <option key={l.code} value={l.code}>
-                  {l.flag} {l.label}
-                </option>
-              ))}
-            </select>
+            <div className="h-10 rounded-lg border border-input bg-muted/40 px-3 flex items-center gap-2 text-sm text-brand-dark/70 dark:text-white/70">
+              <span className="text-base leading-none">🇫🇷</span>
+              <span>Français</span>
+              <span className="ml-auto text-[10px] text-brand-dark/40 dark:text-white/40 uppercase tracking-wider font-medium">
+                {t('glossaries.detail.sourceLocked') || 'fixé'}
+              </span>
+            </div>
+            <p className="text-[10px] text-brand-dark/40 dark:text-white/40 font-light mt-1.5">
+              {t('glossaries.detail.sourceLockedNote') ||
+                'Les templates ne stockent la source qu\'en français. Le multilingue source est sur la roadmap.'}
+            </p>
           </div>
           <div>
             <label className="text-[10px] font-bold uppercase tracking-widest text-brand-dark/50 dark:text-white/50 mb-1.5 block">
@@ -392,6 +391,10 @@ export default function GlossaryDetailPage() {
                 </option>
               ))}
             </select>
+            <p className="text-[10px] text-brand-dark/40 dark:text-white/40 font-light mt-1.5">
+              {t('glossaries.detail.targetLangNote') ||
+                'Choisissez une langue pour voir les traductions correspondantes, ou « Multilingue » pour la valeur par défaut.'}
+            </p>
           </div>
         </div>
       </section>
diff --git a/frontend/src/lib/i18n.tsx b/frontend/src/lib/i18n.tsx
index 4a47e58..a5f17f5 100644
--- a/frontend/src/lib/i18n.tsx
+++ b/frontend/src/lib/i18n.tsx
@@ -438,6 +438,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -1422,6 +1425,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirmer la suppression ?",
     "glossaries.detail.confirm": "Confirmer",
     "glossaries.detail.cancel": "Annuler",
+    "glossaries.detail.sourceLocked": "fixé",
+    "glossaries.detail.sourceLockedNote": "Les templates ne stockent la source qu'en français. Le multilingue source est sur la roadmap.",
+    "glossaries.detail.targetLangNote": "Choisissez une langue pour voir les traductions correspondantes, ou « Multilingue » pour la valeur par défaut.",
     "glossaries.detail.notFoundTitle": "Glossaire introuvable",
     "glossaries.detail.notFoundDesc": "Ce glossaire n'existe pas ou vous n'y avez pas accès.",
     "glossaries.detail.maxTermsTitle": "Limite atteinte",
@@ -2392,6 +2398,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -3317,6 +3326,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -4242,6 +4254,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -5167,6 +5182,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -6092,6 +6110,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -7017,6 +7038,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -7944,6 +7968,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -8868,6 +8895,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -9792,6 +9822,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -10674,6 +10707,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",
@@ -11565,6 +11601,9 @@ const messages: Record<Locale, Record<string, string>> = {
     "glossaries.detail.confirmDelete": "Confirm deletion?",
     "glossaries.detail.confirm": "Confirm",
     "glossaries.detail.cancel": "Cancel",
+    "glossaries.detail.sourceLocked": "fixed",
+    "glossaries.detail.sourceLockedNote": "Templates only store the source in French. Multilingual source is on the roadmap.",
+    "glossaries.detail.targetLangNote": "Pick a language to see the matching translations, or « Multilingual » for the default value.",
     "glossaries.detail.notFoundTitle": "Glossary not found",
     "glossaries.detail.notFoundDesc": "This glossary does not exist or you don't have access to it.",
     "glossaries.detail.maxTermsTitle": "Limit reached",