As i told you in the room and bands told you several times aswell and you still do not understand i will make it clear for you.
Rules are rules, host says no flaming then there will be NO FLAMING.
You speaking russian makes the host have no control over what you are saying to others, this means you are able to insult without him knowing. (before you now complain about this too, NO YOU PROBABLY WOULDNT BUT THERE IS OTHER PEOPLE TOO!)
That is why host decides to tell you off from russian or speak to your russian friends as a first reason.
Second reason is, no matter if you are russian, german, spanish, alien... whatever the hell you want, it annoys others.
THAT is completely reasonable since they can not follow your language and it fills the main room chat. Nothing racist or wrong at all with that.
Sometimes the hosts have to tell someone 3 times to use the international language which nearly everybody in the internet uses as international language: ENGLISH.
It is more about the communication inbetween the community. Hell if we had a fking own toribash language and could only communicate in that, THAT would be the language used only to just keep it understandable for others too and also visible if you flame someone or are just a general dick.
As i said, 3 times or even more hosts warn you and even that isnt enough sometimes. You should be glad you didnt get kicked out already.
I hope you understand that i do not point with a finger at anyone here with saying "you" it is more used for the examples.
I can advise you, if a host asks you nicely to whisper or talk english with your russian friends, do not take it as racism, instead just open a discord or something or whisper them and talk there so the host doesnt have to deal with figuring out what you said or just not knowing that you got insulted.
With this being said, stop being so hurt by that, pull up your guts and grow above it, enjoy the game and respect hosting people, they already have enough stress watching the chat at times you got to think of that too.
Also, to the point of if you plan to host russian tourneys:
Why wouldnt it work? It sure would work out well, you just need the right amount of people and all them being russian. Would be cool to see something like that happening :P Also there you would have the freedom of gathering together with people from your country and just discussing. I believe that would sure be alot of fun!