I can't find a edition of the game in which you can choose the option to use a english menu but the same time the crew of the submarine to speak german! Do I have to look for some foreign edition of the game or is there a patch for it? Does anybody knows something about that? Thank you!
You could just use mods for that purpose.
When you install the game, you install with English as language and the use a German voice mod.
Or install with German and use an English menu mod, or rather such a mod is an UI mod which is a compilation mod of several changes, including an English menu.
If you look at the main page of this forum and look at the top post "Quick Start Guide for SH5" there is a few links there to Subsim web site. Subsims has mods for German Voice.
Carotio I added the link you posted to the "Quick Start Guide for SH5" post at the top of the main page plus a couple other links to the Silent Hunter Mods Forum