You are correct. There is not currently a German translation. If you would be willing to do that, I would be happy to add it to the plugin.
If you've not done POT, PO & MO translations before, you'll want to start here so you can understand how it works.
There is already a POT file included in FPW's languages folder. That is the file that contain all the strings that need translation. With the POT file from the plugin, you'll create a German PO & MO file using a program such as POEdit. Once you've created the German PO & MO files, you'll need to post them somewhere that I can download them and add them to the plugin.
Thanks for offering to translate!