I've tried queue'ing for individual languages before. In the end I get what's on my data center (JP/EN), of course, I can't get French and Deutch in Japan-Land. But when queue'ing for Japanese, why do I wind up with English players sometimes?

I think it's because it also considers your client's language into it. So if you have an under line on E, you'd also get queue'd with E regardless your preferences. That is what they are, preferences, nothing more.

This sounds like it'd work in theory but I don't see it happening very often, or well.