Here's the thing. Server's don't exist to segregate people based on language. They exist to segregate people based on location to the server. This way you should, in theory, play with people with good latency. This creates a set up for a better gaming experience.
Communication is not integral to the game. That is, the game does not explicitly punish you for not communicating. I don't lose 500 health because I didn't warning ping. Communication is all secondary. It is nice, you should communicate, it helps with teamwork a ton, etc... but it is not required by the game. If people speaking in other languages makes you angry for some reason, just say "I only speak English. Please use Smart Pings." and if they don't respond in English, then just mute them and use smart pings. That way you can just pretend they are English speaking players who are not typing.
There are many many players who achieve success by jumping into game, mute all players, and don't type. Do these players deserve to be banned from the server because they refuse to talk to you? Let alone in the language of your choosing? No they don't. If you don't like how someone is talking Riot gave you a way to deal with that, it's the mute button. They also gave us an explicit way to communicate regardless of language, it is Smart Pings.
Before this silly thing comes up, yes I know there is a "refusing to communicate" report tag. However, this is usually for somebody specifically going out of their way to not communicate to you or the team. Such as, they are talking to the enemy team but refusing to talk to your team at all. Even after multiple polite requests to communicate. However, it sounds like these folks are communicating, just you can't understand it. Maybe they can't understand you. If they live closest to that server though, and get the best ping there, then they belong on that server. If you really think they aren't communicating report it to Riot explaining that you asked them (multiple times) to smart ping and they never would. If it gets reported enough then Riot will see it and make a decision. After all, smart pings do appear in the chat log (they are communication).