Thank you all for the replies.
I have zero experience wirh FreeCAD, but I've been modelling with CAD programs for the last 20 years. Checking the Path module I'm "just" clicking around to try out stuff. Since I've seen this behaviour I could not comprehend I've made some screenshots to fo along, as well as my Freecad file, and the STEP file I import.
Playing aroud a bit more I've seen the behaviour I expect, and some that I do not expect. I intend no disrespect to the program itself nor its developers or community. I'm just trying to understand what I do wrong (in thinking). Bear with me.
Correct behaviour, see ictures 1 and 2 attached.
I made sure before even opening the Path workbench, I imported, rotated and saved the part. (yellow plane needs to be the XY plane in the picture). And then I've made a job where the stock shows the model I expect. This differed from the situation I made my original post. So I wondered what did I do different.
The difference was that I selected the "document" if you will (see picture 2 attached) with the "blue cube red sphere" icon. This probably has a proper name I do not know of
This shows the "Stock-stud_welding_assembly" in the same orientation as the model after manually hiding the body.
The behaviour I do not understand, pictures 3 and 4 attached.
When I selected the geometry/solid before I create a job, then selecting "Use existing solid" for stock from the combobox would default to the "cover" body and would show the wrong orientation. Why would that happen if I rotated the entire geometry in the first place? A clone of the rotated body would be rotated in my thoughts.
Scrolling down allows me to chose "stud_welding_assembly" and that shows the proper stock again. I did not see this initially.
It seems like selecting something from the Model view, will default to the first child entry for the "Use existing model" option. I would expect the parent that got selected by me and not the first child.
Anyway, I can work further, nothing blocking, but it would be good to understand.