How is the terrace area calculated?

The only thing we still do not know after 10 pages is what your actual goal is.

Do you want to buy the house?
Do you want to lower the price because of the incorrect information?
Do you want the living area in the purchase contract to be changed to the size you believe is correct?

The only thing we still don’t know after 10 pages is what your actual goal is. Do you want to buy the house? Do you want to lower the price because of the incorrect information? Do you want the living area in the purchase contract to be changed to the size you believe is correct?

Bravo! You have understood my problem.

Actually not, since you still have not explicitly stated your goal. But no matter which of the points represents your goal, the question from the beginning still remains: Why haven't you spoken to the seller yet?

Actually not, since you still have not explicitly stated your goal. But no matter which of the points represent your goal, the initial question remains: Why haven't you spoken to the seller yet?

This question has long been answered

I have now specifically looked at all your posts again and unfortunately cannot find any information about a conversation between you and the seller. What did he say about why you believe that the stated living area is not correct?

Stupid question: if I complain about this now, we won't get the house ... What is the best way to proceed when the square meters are clearly incorrect?

That was probably what the OP meant by answered.