Navigate to System Definition > Plugins and install the I18N: French Translations plugin.
Click the gear icon and change the Language setting to French.
Navigate to the Base de connaissances module (Knowledge Base).
Click Recherche avancée next to the search bar to show the advanced options.
Set Sujet to Email and Catégorie to Trucs et astuces (Tips and tricks).
Search for any term.
Note that Catégorie has changed to -- Tous --- (All).
If you follow these steps but with the Language set to English, the Category value is retained.
Because the Topic/Category dependent choice list has been deprecated since Fuji, this behavior is expected. For information, the advanced search is called in the kb_advanced_search UI macro.