I think it would be amazing to release more and lesser spoken language textbooks. Not only would it be educational, but it would be a cool way to raise awareness about some of the less common and slowly dying languages out there -- and a nice tribute to the cultures that built them.
As nice as this would be, I know Subeta is trying to get away from real world things, so I can't see it happening =<
While this would be truly awesome, there are over 7000 languages in the world. Which would you take, and which would you leave? The top 10, 50, or 100 most spoken languages? The hundreds that are nearly extinct? It's sadly unfeasible. Just research it yourself if you're interested. c: link