I just installed Zorin 15.3 Lite 64bit under VMWare and chose English, Belgium with Belgium keyboard, and set the location to Brussels in the installation dialogue.
Indeed, the calender shows day and month names in German:

Opened Settings -> Language Support, then selected the Regional Formats dialoge, only to find that is was set to Deutsch (Belgien):
Changing this to français (Belgique):

Needed to log-out, log-in, and voilĂ :

Not sure why the installation program chooses âDeutsch (Belgien)â as default, instead of asking.
HTH