I think I remember that on either testing or one of the times they were trying the chat server split on prod, it became possible to type non-Latin characters. I don’t know if I’m remembering wrong though, it has been a while.
I think that at least, people should be able to type non-Latin characters into the chat. I think it would be reasonable to restrict account names to only using A-Z letters (as it already is, though I’ve seen a few strange exceptions recently) for moderation/support purposes.
Of course, this introduces some more spam potential because omg non-standard font can do so many things with it, but really it only exacerbates an existing problem (misuse/abuse of the chat) that Deca needs to deal with in a better way.