Unpredictability of construction costs - Will the project fail because of it?

I read a raw construction height of 250cm and a floor structure of 25cm:

So this will not be living space, in Bavaria it is intended to be 240cm.

What you are referring to are the height reference points, not the actual room height.

It is best to check again with the energy consultant. Although he has seen all the plans..

The property would have two levels, so it does not have to be completely filled or excavated.

Sorry I think nothing can be read, I will try again right away.

Sorry I think you can't read anything, I will try again shortly.

You can read the plan, only the site plan of the property is missing?

What you are referring to are the height reference points, not the actual room height.

I had already suspected the mistake from the floor plans, as there were no room heights yet. But the story height of 2.60m. But since we both arrived at a ceiling height of 2.25 m, everything is fine.

In fact, we were not aware that we were complaining at a high level. In all the new development areas, there are huge mansions with all sorts of bells and whistles, against which our planned house appears totally small and simple.

Well, if you plan beyond your personal needs, instead of a nice small 1.5-story house you plan 3 (full) stories (even if mathematically it is less), treat yourself to an expensive granny flat that is supposed to be for the teenage child, then that is planning on a grand scale. Of course, when costs then explode unpredictably, I as the builder, who has dealt with needs and extras for weeks, know exactly where the cost eaters are and where I can first start to save.
And you also have to see yourself where you stand: the huge mansions in the area are from a different building era, possibly from earners better off than you, and honestly: you don’t build it as the neighbor needs it, but as you yourself need it and can also afford financially. When interest rates were 6%+, things were more modest as well. Everyone must and should use their own time, as it is offered to them.

Actually, we were not aware that we were complaining at a high level.

Yes, that is complaining at a high level. I built 1.5 years ago. Without a granny flat, without a basement, without a garage (yes, even without a carport).

In all new development areas there are huge mansions with all kinds of gimmicks, against which our planned house seems totally small and simple.

That is the real problem, you compare yourselves with others whose starting situation you do not sufficiently know. At first friends and relatives also came to us and complained about how we could build without a basement and without a garage. But some of them are now also looking for a property and have understood it now.