Thank you all! Every day on the construction site, I feared that... As mentioned above, this would be our second time building. We will definitely not take the architect from the first time again... good design for our needs back then, but not future-proof (kids are now out of the house). Above all, he had no idea about construction management and the many small crucial details and was on the construction site far too infrequently. We have painfully learned that until today.
It will take a little longer. So far, there are many ideas in mind and a reserved plot of land. We are still in negotiations with the building authority because the development plan does not allow a flat roof, which is a must for us. I just received news today that, contrary to expectations, it looks good; it should definitely be decided within the next 2 weeks. It will almost certainly be concrete, since it has long been decided here that the first floor will protrude beyond the ground floor and this side (south slope) will be more or less completely glass. Outside either exposed concrete or white, we'll see.
When the time comes, I will start a new thread; the discussion here in the forum is great.
Thanks for the recommendation, unfortunately even further away from us than some architects in BW that we like.