Ja, ich habe mich auch im deutschen Forum gemeldet, dachte aber hier wäre effektiver...If you'd rather do this in the German forum, ok with me, though.
I didn't recognize .tar.bz2 as a zip file. This unzipped to .tar file, which is also a zip file, and this unzipped to dict.xdxf and icon16.png. I tried converter.exe dict.xdxf ital (with still the 3 .txt files in the subfolders copied from eng) but again, nothing happened. I don't understand how to make those .txt files.
Re keeping the dict up in PB, now it works! Apparently this does not work when in Adobe Reader, though, only in FBreader. Then it stays up fine, as you said! Great! I'm sure Italian is just a step away...