I guess the reason why nobody answered my question about german radio messages is, that there is no mod...
Additionally I have to report a problem with a savegame...Before entering the english channel I saved. In the channel I sank some ships but unfortunatly I had to quit the game. When I loaded the savegame I had the marks for the ships on the navigation map, although there was no tonnage in the log...To make it clear: I sank the ships after the saving and didnt save again. I also didnt load an autosave. Never had this before, is this normal?