Floor plan of a 200m2 house, your assessment?

What in what I wrote makes you assume that we did not do it exactly as you describe?

Is the question serious? You have a budget of 600k and here you present an architect's design that can cost almost twice as much. The assumption that you did not do it exactly like that is therefore obvious. Despite your detailed answers, it is still not clear where this is supposed to lead. The objection that downsizing is not so easy is correct and important. It will then no longer be this concept, this style, just smaller. It will be a completely different style, a completely new concept, something completely different. Unfortunately, "just" saving 50-100k but keeping the building structure as is won’t work; you would have to save 300-500k. You have left many questions unanswered; it is noticeable that you did not expect this budget overrun, not to that extent. So shake yourself off and start over, with a clear budget. Or increase it and build this great house exactly as is. In my opinion, there will be no middle ground.

write me your experiences with (artistic/)creative and inexpensive solutions like

We also want to possibly use polycarbonate sheets in some areas that let in daylight.

Hmm, no experience, but that would not be allowed at all in the residential construction sector here in Germany (which includes single-family houses), or would be contrary to any contemporary energy regulation with a U-value of 2.x. Austria is probably no different in this regard. At least that is my current knowledge.
Or is there already something new with better values? Do you know anything? Do you have a manufacturer? I personally know that the material is very weather-sensitive. It is rough in itself, and algae quickly settle on it.

What in what I wrote makes you suspect that we didn't do exactly as you described? I think there are a lot of assumptions (even accusations) being made here, which I find unfortunate because it detracts from the actual content.

What makes me suspect that? Your statements here in the forum.

Maybe I am reading it wrong or you are expressing yourself awkwardly?

What you presented in post #1 is a draft. Whether you call it a preliminary draft or not doesn't matter. You stated a budget for it. Then you were repeatedly told that the budget and (preliminary) draft don't match. Not even with more buffer. Then you want to adjust/shrink the draft to also become cheaper. Later you wrote that you want to follow Plan A and only pursue Plan B if that is too expensive. The latter sounds like you first get offers in and if it's too expensive, you replan.

If you told your architect the 600k budget for the house and that draft came out of it, then the architect is not good. Not in what she designs (I think the draft is great) but in no way fitting for you because simply too expensive. Why I don't find it good from a design point of view, I've already written - downsizing doesn't work in house construction in my opinion.

One more substantive thing. The style you like (which I also happen to like) is in 99% of cases very expensive. You think these clean lines are not costly because with exposed concrete screed you save on the covering etc. But usually it’s the opposite. There are fewer companies that offer this because processing is often significantly more complex. Special treatments necessary (sanding, sealing, etc.) and that makes it expensive. Same goes for concrete stairs.

Now to say I leave this out and that out and make the staircase like this or like that or place it somewhere else results in a completely different design. That simply has nothing to do with the original idea anymore.

That’s exactly what I already said, “Once through the grinder”… You could almost say, “Reset button, here I come.”

Hmm, no experience, but that would not be allowed at all in Germany in the residential construction sector (which includes single-family houses), or it would be contrary to any contemporary energy regulation with a U-value of 2.x. Austria is probably no different. That is at least my current knowledge.

I have read/heard different things, what you wrote, but also that polycarbonate has meanwhile reached very good values, is more shatterproof, lighter, and much cheaper than glass, and is very suitable for, for example, light strips. It could possibly also be an option for me as a railing. I also know many very aesthetic examples where it was used in museums, etc., but also in residential construction. But I would have liked to hear practical experiences.

that polycarbonate has meanwhile achieved very good values, is more shatterproof, lighter and much cheaper than glass, and is very suitable, for example, for use in skylights.

Yes, you can achieve U-values below 0.80. Yes, it is suitable for skylights. No, not for regular windows, because you always have frosted glass and cannot see through it. Cheaper? I don’t think so, because you have to contact specialized companies, which are more active in industrial and commercial construction. I don’t know of any manufacturer/producer for regular residential construction.