Add Ability to Sort streams by language
Could literally be added here in the channels page http://i.imgur.com/5w1iyXi.jpg
You even ask for the language in the dashboard when changing title.
MUST have a better "in-your-face" way to sort streams by Language on the Browse page. That would make things easier for all viewers trying to find language-based live streams. A good set of filters (not tags) will definitely improve browsing and discoverability.
The ability to sort by language already exists: http://help.twitch.tv/customer/portal/articles/1771242
From my experience, it seems that quite a few people aren't aware of this functionality. Twitch do realise that many of their users are bilingual/multilingual and that sorting options are important to those who use their platform. I too believe a more prominent language sorting option in the directory, as you suggest, would improve the user experience.