According to an Apple Support website, it is possible to change the language of the operating system (from e.g., English) as follows: Click on Apple Logo (top left on screen), click on System Settings (Configuration), Click on General, click on Language & Region, Under Preferred Languages, drag Français to the top of the language list to make it the Primary Language. You may need to reboot the Mini Mac. On my Mac mini, my Primary Language is English. If you are first installing the OS and configuring the new Mini Mac, you will be asked for region and language. Hope this helps.
