Hello Holger, I checked the Weblate platform. I am familiar with Weblate, using it on translate.codeberg.org in my own projects.
I am confused about your configuration. I do see 6 components in the "Debian Installer" project behind your Weblate link. "sublevel1" to "sublevel5" and "Debian Installer (Glossar)". The later do have German but without strings. The other 5 components don't have German. But I am sure that the Debian Installer is available in German. So where are the translations? Anyway, it is great to have Debian using Weblate. This is IMHO very important and also to my own experience improves translations and makes it much easier to approach (non technical) translators. Regards, Christian Buhtz