Once the first translations are out in production adding further languages is just a matter of finding a skilled translator or a good quality translation service.
But as the app evolves we want to ensure that we keep the locale files in sync and we have some way of seeing where translations are missing. The first step is to identify the additions to the master language that need to be updated in the translation languages.
I found I nice tipp over at stackoverflow and I expanded on the logic a little bit
Try now without obligations