It is a known fact there are plenty of people out there who aren't very capable in the English language. And having those people in the same spectator chat can be a bit annoying.
And I guess those people don't (always) like reading English all that well either.

And a lot of the eastern players also just type only a few words per line which makes it quite spammy.

Maybe an option to have more spectator chats for other languages just like you have the option to select when searching for games?
You can either have 1 English and 1 global for other languges or you split them up more like the search and one for 'leftovers'?