As you know, SABnzbd is available in different languages.
For this we rely completely on volunteers. We call on translators (you!) to complete and check translations.
You don't have to know about software development to contribute to translations. There's a very user-friendly website that organizes the effort at https://translations.launchpad.net/sabnzbd/0.8.x
There are some things to watch out for. Be careful to replicate special constructions in the texts, especially placeholders like %s. The %s text is used to substitute parameters.
Simple example: "The file %s is missing" will look like this in the user interface: "The file john.rar is missing".
The text often contains hints about the context in which a text is used, for example: Located in SABnzbd.py:613 [Warning message]
Please contact us first if you want to start a new translation!