> then it would certainly be nice to use one language for everything, from front-end, back-end to distributed computing stuff.

People say this, but it's not that helpful, IMHO. Front end and backend have different concerns, usually different teams, and using anything other than the preferred language for a client platform tends towards clunky UX.

You can do some sort of core networking library that's shared between clients, and I guess there's reasons you might want that to be Erlang, but integration feels like a lot of work when you can just deal with it in another language. Client side concurrency is so much less than server side concurrency, it'll be fine.