Good morning,
where do you actually want to build? In NRW or RP?
I assume that your design complies with the development plan, so I find it well executed - except for minor details. Contrary to the prejudices described here, I also think that the staircase shape is a good choice and would not change it if I were you. To bring light into the attic, a daylight spot is sufficient; in the evening, the light switch will be used anyway. Light strips above the interior doors also convey a sense of brightness.
What I do not think is well thought out is the location of the bathroom above the AZ of the ground floor. I think a swap between "Child 1" and "Bathroom" is worth considering. Otherwise, the comparatively low knee wall can be well integrated through clever furnishing. Moreover, it has repeatedly proven in the past that sloping ceilings create very cozy rooms; children don't care anyway, as they use the entire floor area and not just the living area according to DIN.
It can be debated whether too few windows are planned, and whether the exterior view does not meet the eye’s desire for harmony. On the other hand, people live inside the house, not outside it, and the idea of life inside the house also needs to be implemented. A good compromise here could be the alternation between floor-to-ceiling window doors and light strips. It flatters the optics and ensures sufficient light in the house.
You write at one point that the house costs—how high are they projected?—are slowly reaching a point that must not be exceeded. Why then must it necessarily be a clinker house?
Rhenish greetings