Design for a single-family house with 160-180 sqm - suggestions for improvement?

In your case, simply too much information is still missing for the matter to even get a framework within which to operate. You can't just throw down a house floor plan when you don't even know what you need. And you also can't expect people here to make you thousands of proposals, which you then reject because, of course, they don't fit your secret life plan.

You can't even manage to determine and justify a spatial requirement. It's casually said, it basically fits as in the initial draft. Only the garage is being moved back and forth – yes, that is important. Well then build it that way if it fits so well.

You have a difficult plot. In my opinion, a slope is always a case for a real architect. But even the architect will want to know what you really want and what you don’t. Nobody has the time or desire to plan castles in the air.

You have certain ideas, people with experience comment on them, and because your ideas are not praised and hailed as great, you claim that helpfulness looks different?

Your seemingly sulky response to Haydee’s question is rather counterproductive. To the question of what you wanted, you then replied:
"How much storage space?: none so far" or
"...If possible on the sleeping level yes/no (that’s where the laundry accumulates): so far 4 floors down in the basement"

No one wants to know what the situation is NOW, the question was: decide what you want!
Become aware of what should be better than in your apartment. Why do you want to build, what are your wishes? Whoever doesn’t know what they want, gets what they don’t want!

Just let your imagination play a little. If you have been living in a multi-family house up to now and have to trudge 4 floors down to do laundry: should it stay that way? How would you like your life later on? Do you want to lie in the bedroom and listen to music or would you maybe like to consciously go to another room soon, where you can perhaps enjoy a great view or a nice chill corner while listening instead of the bed? Just because that may not work today, doesn’t mean it has to be great for later.

You are getting carried away!
Go out and get inspired. Model home parks, new development areas, browse magazines. Dream around and first of all imagine what would be great for you.
But the HOW is a matter for an architect afterwards. They know their stuff, they know how to best plan a garage on a sloped plot and also how the arrangement of two staircases in a house should look like. The professional will then help you turn your ideas into a house.

Think about it: if you have previously lived quite normally in a rental apartment in a multi-family house, many things are different, and a single-family house is an improvement for almost everyone. Therefore, you are dependent on the experiences of others.

What bothers you about the apartment?
What bothers you about the apartments of friends?
What would you like to have differently?
What is your desired furnishing?

Visit model home parks

And what do you want now?
Do you want to continue storing suitcases in the bedroom and Christmas decorations in the living room?
Do you want to still go to the basement to do laundry at 75 with gout?
Do you really want to rent it out, or is it just "well, if we have it"? Wouldn’t it be better to separate the Airbnb area a bit?
Do you need a study?
So the room upstairs is initially superfluous and only there so the bedroom does not become even bigger.
Would you maybe like to listen to music under an open roof truss with a view of the sky?
Is the kitchen with 7 sqm sufficient, and should it be closed again?

You can have endless suggestions here. You need to know what you want; otherwise, the house will never fit.