Feedback floor plan - size and price ok?

The house can cleverly be made just as large with half the area.

yes, gladly - but how, I wonder

Then just assume 2000 EUR per sqm for a new edition + ancillary construction costs + garage + outdoor facilities + kitchen + other furnishings or special requests. Don’t forget earthworks for a hillside location and more expensive outdoor facilities on the slope (here and there a retaining wall). You will have to come to terms with the fact that it will then be a completely different house. But many have had to go through this process before. It will be fine!

One more quick question, where are you building? Maybe I overlooked it, just to get a sense of how to estimate the regional prices.

The architect is not included in the budget, right?

My hairdresser tells me every time that customers come to her with pictures of hairstyles and want the haircut shown. In her opinion, these are the most annoying customers.

Maybe the architect misinterpreted the pictures, and with just a few communication errors, a project can quickly get off track.

Nice analogy - and I think a fitting analysis of the situation.
But who goes to the hairdresser and says: "make something out of it"?

One more quick question, where are you building? Maybe I missed it, just to get a feel for how to assess the regional prices.

Near Frankfurt - probably doesn't make it any better...

Architect is not included in the budget, right?

no - it's separate