Congratulations! We're thrilled when our authors succeed with their books, and look to bring them to other languages.
In terms of translation services, we don't offer anything like either the service itself or some kind of marketplace to connect authors and translators.
All we offer is the ability to connect books to their translations via their landing pages, once the translation is done. So, for example, the book Everyday Rails Testing with RSpec was translated into Japanese and then into Chinese, and we show the translations clearly in the About the Book section at the top.
We also make it easy for translators to start, of course, since they can just start with either a clone or fork of the original language book repository. Using the same GitHub repo, or a fork of the original, can be helpful if you're trying to do things like keep images in sync between the original language version and the various translations, etc. However, in terms of finding the translators to actually do the work, unfortunately for now you're on your own...