I received the bounty today (thanks again, davout)
I also asked davout to update the thread, maybe he will request additional translations then

I'm pretty much done with the translation now, I messaged davout over Github so he can review the changes.
I will keep you in the loop.

I have almost finished extracting all strings and doing the german translation.
Follow my progress here.
Davout is following the branch and will pull the changes when I'm done, other translations should wait until this is done.

I would like to contribute a German translation.
Here is my fork with the added base locale: https://github.com/vlaube-de/bitcoin-central/
I haven't really started to extract any strings to yaml files yet, but would be happy to help.