I try to read the answers, understand them, and think a bit before writing my first reaction. I will try to check in and respond more often!
We already had the stairs more central with a separate kitchen-dining and living room, we didn't like it as much as the combined version. See:
We have already discussed moving the entire cooking-dining-living area to the upper floor, but it was "rejected" because the garden access would then be "lost". However, only putting the living room upstairs is a very interesting approach and worth more detailed consideration. Disadvantages I see: The family "spreads out" more over the house, e.g., when cooking/watching TV/playing? With small children over 2 floors: At least this is only a time-limited problem. For visits: upstairs or downstairs? And both rooms probably feel smaller separately than combined. Where to put the stove? I will take some time over the weekend to try to draw this with correct measurements to see if it can work out.
In my opinion, the terrace facing NW does not work because of the neighboring buildings. The house with the gable is in this position on the overview plan, this is the house with the photovoltaic system.

The rotated upper floor is also somewhat due to the adjacent building, in order to achieve proper water drainage and aesthetics, while having as many windows as possible to get light. From the direction of the driveway:
Again on the topic of the utility room ;-) How should the optimal utility room be built then? In the technical room? With additional ventilation? What is the "best practice" here? It seems pointless to me in the hallway, as I wouldn't even have the option to ventilate through a window. Controlled indoor ventilation, as already mentioned, is still under discussion (budget...). Or is only the mixing with fresh laundry the problem?
Thanks! :-)