It would be great if we could know a player's spoken language! Co-ops have the setting option, but anyone can join, if Open, whether they speak the same language or not. Assuming there can be no hard-stop or language matching feature, could you add a player's spoken language to the Profile?
Our co-op is EN and has someone whose name is in possibly Chinese. We don't know what to call her and she never chats, I don't think we can communicate with her. Our co-op was set to Open when she joined. We've changed that now.