Warning/confirmation when deleting a page containing used XClass on subwiki is displayed in Main Wiki's language

STEPS TO REPRODUCE

1. Start an XWiki instance with English language (Monolingual)
2. Create a subwiki
3. On subwiki, go to Administer Wiki > Content > Localization and change the Default Language to French
4. Create a page ("PageClass")
5. Edit it in Class mode and add a property (e.g. 'Time1' / Type: Timezone)
6. Create another page ("Page2")
7. Edit "Page2" in Object mode and add a 'PageClass' object
8. Go to page that contains the class ("PageClass") and click "Plus d'actions > Supprimer"
9. Click "Supprimer"

EXPECTED RESULTS

The warning/confirmation message is displayed in French, the language of subwiki.

ACTUAL RESULTS

The message is displayed in English, the language of the Main Wiki.