Blender is not using the system language

[JanMaul]

If the system language is set to german, Blender still uses english.

[aaaaalbert]

Some related info: I couldn't find out from a quick web search whether Blender is supposed to ignore the system language and default to English on purpose, or if it's an oversight to not use the system language. The language for different parts (!) of Blender's interface can be set when the program runs – there are guides for this, see also the official docs.

However, only about 40% of the Blender GUI has been translated to German so far; the manual, only 2%. So one would likely encounter lots of English GUI messages for the time being, even after switching to German.