The Chapel Rock Campaign
The Order uses Latin as its primary means of communication, being one of the few places where Latin is still spoken. So that’s your party common tongue, but since no one else speaks it you need a few other options.
Crusaders will likely speak Langue d’oc (Occitan) or Langues d’oil (…French, basically); this was what Richard spoke.
Most of the island speaks English (what we’d call “Middle English”).
In Wales, they speak Welsh. Again, we’d say “Middle Welsh” but they wouldn’t.
Bears speak bear, which consist of not actually speaking because they are bears.
Feel free to record “Living Language: [place I was born]” for now and we can research the details later if need be.