That might sound stupid, but is it possible to use 2 different Webbrowsers with the same O365 account to view the complete Admin in german and english?
When asking for help in english it is quite helpful to have the admin too in english.
In general the portal should detect the browser's language setting and use the language selected there. You should also be able to change it from your profile settings, but in some cases the option will be missing there
Yep, if your user has selected English as default language and he has one of the browsers configured in German, it should see the Admin Portal in that browser in German
