I think the source of the problem is the per-language server, this was a good decision at the beginning that is slowly biting in the back now.
Think about it, does vatsim has regional servers? or any other multiplayer game/sim for that matter.
The nature of the sim and voice chat is surely a problem, not sure how to fix that.
For text a simple menu of pre-made sentences that gets translated in you local language would be enough (also with ai-generated voices this could be heard as voice chat on the radio).
I personally stopped to play multiplayer lately for other reason, the new DLC streched a bit the map and that's good, but some problems remain such as
can't set a custom season (why?)
can't set a custom time (even as an offset of UTC)
can't choose a livery (again another cheap win)
can't choose loco/composition/service (complex I understand)
So while multiplayer gives interaction with other players the restrictions imposed by the current technology stack makes it very rigid.