I believe the translations were does by volunteers in italki. We don't have it in our language (Bengali) yet but we can voluntarily help italki translate the whole site to our language by translating one short sentences at a time. Here is the link for translating italki: http://www.italki.com/translate/default.htm I don't know if I exactly answered your question but I would be glad to have helped you ^_^

I guess because previous translators haven't done that great a job? http://www.italki.com/translate/ - I guess that even though it says 100% you could probably still improve it.