The site as a whole is a good start, I'd say. I like the filter setup, it may get unwieldy as the number of languages/subjects multiplies, so you'll want to think ahead on scaling.

I think a little less text in the bubbles on the about page is a good idea. You can catch it all in the backup text below if you've caught the reader with the short version above. But the page layout looks pretty good overall. Maybe give it one more coat of polish, then try a couple of divergent ideas and mock them up, then ask us to take a look and compare?

I'll admit to being favorably prejudiced toward your site's purpose, BTW, so my response may be more enthusiastic than you'd get from most of your targets. ;)