diff --git a/Models/HumanLanguageCatalog.cs b/Models/HumanLanguageCatalog.cs
index 8ed2b33..ab913d3 100644
--- a/Models/HumanLanguageCatalog.cs
+++ b/Models/HumanLanguageCatalog.cs
@@ -103,6 +103,20 @@ public static class HumanLanguageCatalog
             map.TryAdd(normalizedAlias, normalizedCanonical);
         }
 
+        // Force an alias to a canonical, overriding whatever culture enumeration inserted for that
+        // key. TryAdd is not enough here: on a host whose ICU data carries a "Norwegian Nynorsk"
+        // culture, the enumeration below claims the key "nynorsk" -> "Norwegian Nynorsk" first, and a
+        // later TryAdd("nynorsk", "Norwegian") silently loses. That made "nynorsk" resolve to
+        // "Norwegian Nynorsk" on the CI runner but "Norwegian" locally — the same host-ICU dependence
+        // this seeding exists to remove. Overrides must win regardless of insertion order.
+        void Override(string alias, string canonical)
+        {
+            var normalizedAlias = NormalizeKey(alias);
+            var normalizedCanonical = NormalizeDisplayName(canonical);
+            if (string.IsNullOrWhiteSpace(normalizedAlias) || string.IsNullOrWhiteSpace(normalizedCanonical)) return;
+            map[normalizedAlias] = normalizedCanonical;
+        }
+
         // Seeded FIRST, and deliberately not derived from the host.
         //
         // This table used to come only from CultureInfo.GetCultures, which returns whatever
@@ -145,14 +159,20 @@ public static class HumanLanguageCatalog
             Add(native, english);
         }
 
-        Add("norsk", "Norwegian");
-        Add("bokmal", "Norwegian");
-        Add("bokmål", "Norwegian");
-        Add("nynorsk", "Norwegian");
-        Add("mandarin", "Chinese");
-        Add("cantonese", "Chinese");
-        Add("farsi", "Persian");
-        Add("persian", "Persian");
+        // These collapse regional/script variants and common exonyms to the umbrella language a CV
+        // means. They must beat culture enumeration (see Override), because ICU carries "Norwegian
+        // Bokmål"/"Norwegian Nynorsk" and "Chinese (Simplified/Traditional)" as their own cultures.
+        Override("norsk", "Norwegian");
+        Override("bokmal", "Norwegian");
+        Override("bokmål", "Norwegian");
+        Override("nynorsk", "Norwegian");
+        Override("norwegian bokmal", "Norwegian");
+        Override("norwegian bokmål", "Norwegian");
+        Override("norwegian nynorsk", "Norwegian");
+        Override("mandarin", "Chinese");
+        Override("cantonese", "Chinese");
+        Override("farsi", "Persian");
+        Override("persian", "Persian");
 
         return map;
     }