...first...
now my answer...
I've started to learn some others languages, to have better way to communicate with people in the world, and I will be so glad to talk (or try at least) them in his native language (this will take a time ofc, but... all I need is time)
now seriously...
Servers haven't restrictions about language in chat (and won't have).
Like Elary said, we use english because is more common in the world, and a high % in server know it,
so this is better for we can understand between us online.
Aside this point, there are a thing named "courtesy"... probably some know about it, but probably others not,
or even maybe that someone (don't offend, I'm not generalizing) haven't had enough education to know and apply it in the world
_______________________
one more: if you think/suspicious that other players are insulting in game online using "strange " language for you, only take some screenshot and post a complain about it, saying server, data time and name of bad guys, for we can read and translate logs...
will be a pleasure for us to deal with them
ps: You think that his purpose they will never get it, if they do so only they him understand, so, why worry?