try it like this

app.py

@@ -33,17 +33,18 @@ def filter_languages(search_text, selected_languages):
     
     # If no results, show a message instead
     if not filtered:
-        filtered = ["No match found..."]
+        filtered = ["No match found"]
     
-    return gr.update(choices=filtered, value=None)  # Keep dropdown open and selectable
+    return gr.update(choices=filtered, value=filtered[0] + "...")  # Keep dropdown open and selectable
 
 def add_language(selected_language, selected_languages):
     if not selected_language:
         return selected_languages
-    selected_list = selected_languages.replace(",,", ",").split(",") if selected_languages else []
+    selected_list = selected_languages.split(",") if selected_languages else []
+    selected_list = list(set(selected_list) & set(languages.get_all_supported_languages()))
     if selected_language not in selected_list:
         selected_list.append(selected_language)
-    return "" if len(selected_list) == 0 else (",".join(selected_list)+",").replace(",,", ",")
+    return "" if len(selected_list) == 0 else (",".join(selected_list)+",")
 
 
 with gr.Blocks() as demo: