not sure exactly but might be the supported fonts that are either in your browser/miniclient or pc itself

Hmm.

Yes, I also think that might be the case. It is the same here on my laptop, there are few names or special characters that I can't see from Mini-Client (It is not supported by the program itself, I assume) but appears when I'm using Google Chrome. Anyway, using such special characters in-game is not advisable since it will cause you some problems in the game like Inviting, Chatting, or even receiving event rewards in the in-game mail.