I agree, many streamers can speak more than one language and they are making their own way of letting viewers to find them.
For example by putting like "[ENG/JPN]" all the time in the title.
It has to use certain number of characters in the title which supposed to be for what that stream is about. Also there is so many variation to describe languages.
Someone might use "JP/EN" or "日本語/English" and this inconsistency makes so much harder to find multilingual streamer.

Even making limit number from 1 to 3 helps us a lot I think.