I would be in favor of this only if there could be filtering as proposed, at least in the RSS feeds from the planet. Perhaps a different feed for each language? That would be reasonably simple to implement. Perhaps even leave the existing "default" feed English since that is effectively the de-facto language, and then add language-specific feeds...

Whatever happens, I definitely _don't_ want to have scrape through even more syndicated posts from the planet in my feed reader that I couldn't read even if I wanted to.