Floor plan design for ground floor - ideas?

The last straw would now only be if the study were also to be a bedroom for the elderly.

I actually assume: the combo "office approx. 12 and shower in the guest WC" is the classic that gives you the feeling of having prepared. The fact that this contradicts having a basement, the builders do not see. Nor do they see the incorrect room dimensions of the office - not furnishable with bedroom furniture.

we definitely don’t want the study downstairs facing southwest (the living/dining area is supposed to go there).

That doesn’t matter at all and doesn’t change the living room situation since no window is planned in the NW. It’s completely irrelevant for room effect and lighting situation.

From above, we don’t even know whether it’s an attic or upper floor.

You can infer that: attic.
But I’m tired of always thinking along and pulling out my crystal ball, which can also be wrong.

It doesn't matter at all for the spatial effect and lighting situation.

I have to add: the room situation is much nicer because the windows are arranged at the corner. The room is therefore much nicer and also easier to furnish than the clumsy left version. In addition, the right design has further advantages.

Besides, the right draft has further advantages.

Yes, plan 2 opens up the possibility to swap the sofa/TV area with the kitchen area, thereby having the ideal terrace proximity for the kitchen and the retreat area "living, chilling, reading, watching TV".

That can be derived: DG.

From what can you derive it? - "Plan2" would require at least a considerable knee wall due to the stairs.

What can you derive it from?

Just accept it as it is.