Please clarify the "etiquette" speaking in english

[Bobo]

Well, there are some ppl who can't speak English and what should they do to communicate? To give an example, there's a long time player (very good player and a very nice guy) named Zublon. For most of the time he speaks nothing but sometimes he gives a warning to the team or similar and he can only do it in Russian.

Also, should we apply the same rules to voice chat during events?