[WHM API 1] createacct, invalid value “fr” for the “language”

Hello guys, My company have been using the WHM API 1 for a while now, working like a charm :-D. However since today, we are facing an issue when we want to create new cPanel accounts. It appears that the 'fr' code language given in query params is no longer recognized. At first, I thought the API entrypoint changed but the documentation about it is the same as before :

language

string The account's default locale. Note: This value is case-sensitive. For region-specific locales, use the ISO 639-1 code, an underscore (_), and the Thanks. EDIT: I'm using 'cpmod' => 'paper_lantern', maybe it has something to do with that considering this theme is deprecated (need to test) EDIT2: Tested with 'cpmod' => 'jupiter', issue is still the same