What I found so far is:
Sequoyah, plugin for eclipse but non existant for Juno, so I have not tried it.
aiLocalizer, an external program written in C# (needs .NET framework, but I can live with that) but this messes up the xml. I would like the result xml to have the translations in the same order, and with the same inserted comments as the source xml.
MOTODEV Studio, discontinued.
I'm not looking for any online tool, but rather one that I can have locally and that helps me figure out which strings aren't already translated to the different supported languages.
Anyone has an Idea?