Floor plan of a single-family house, 2 floors with basement, approx. 190 m², plot approx. 440 m²

: why so sad... We have to like the house... As long as it is basically buildable and not structurally impossible or something...

I adjusted a few small things on the ground floor and upper floor and improved the basement. And furnished it.

That is certainly true. But you asked for criticism. You got it, but you don’t want to accept it – that’s also okay. But the floor plan remains rubbish. The fact that it is buildable does not make it any less "rubbishy". And it is still pointless to try to "optimize" this floor plan. The best possibility for optimization was told to you: throw it away and have a professional handle it. They can manage to fit your wishes into fewer square meters, which saves costs and you will get a nice, individually planned house with a functional floor plan.

P.S.: again, not meant to be unkind.