Calculated construction costs incomprehensibly high

Yes, I also think that the prices were set rather at the highest level. That is exactly my problem, that I don't know any average prices. I wonder whether we will have to give something up in the end, or if the prices themselves are already set very high and we can still get something out of them.

I only know the price level in Bavaria, we were significantly below that. Obtain additional offers.

Here: 140sqm + basement all included (!!) 350K, Bavaria, property available

I have a permit created by a known architect,

The permit, here a building permit, is typically issued by the authorities, that is the municipality, the city, the district, whoever it may be, but not the known architect. Do you mean a permit planning, that is the documents that the builder submits when applying for the building permit? Everything about the costs has been said in my opinion. It will be cheaper if you save on the services (square meters etc.). The cost estimate becomes more reliable if you obtain comparative offers from several general contractors.

Should reach KFW 55 if possible.

According to his calculation, the house only reaches KFW 70

Did your architect make a calculation, or roughly put the house on paper and said it will probably be fine?
And on what basis does he determine that the house only meets the Energy Saving Ordinance 2016? Because of the used materials/wall thicknesses, or because there is no ST?

Earthworks: 12,000

Is that fixed, or can that still change?

He didn’t even include solar thermal and fireplace in the calculation

Without ST, KfW 55 will be difficult

Otherwise, I see many nice things that cost a lot of money (e.g. venetian blinds).

But this is also your first offer, right?

To the construction expert: Shouldn't the construction partner list the trades individually?

Only if individual trade awarding has also been agreed upon; that is, if you want to build with an architect and he calls for bids for the trades on your behalf, so that you can decide whom to trust for each. A general contractor/general supplier or also an appointed construction manager will not disclose individual trade prices; why should they? Rhineland greetings