Wrong document types assigned

[CubE135]

Hi, im having some trouble with the assignment of Document Types when uploading new Documents.
I have defined the following Document Types:

Then i uploaded 5 Documents. The first 4 are recipes. They include the word "Rezept" or "Zutaten". But they get very different Types assigned.
The 5th Document was a Invoice that contained the word "Rechnung" but somehow got the type "Lohnzettel", which makes no sense, as that type requires 3 words, which do not exist in the document.

Why does this happen? This makes no sense to me.