Adding All Languages into English Client

Is it possible to add all languages into the English client? Sometimes, I'll see square boxes if it's not English. Or there is a way to add the fonts ourselves?

Thank you. Appreciate it!

 

AFAIK it's a language that our computer is not recognizing but I may be wrong.
EX: If a korean, japanese or russian tried to world chat and those language are not in our system.
coz on my other computer its fine.

 

And how do I add that to my system? If you don't mind answering. I already have the specific language set up on my keyboard. It's still square and unable to display/read. What else do I have to do? Thanks.