Sampling and execution drawing with content differences

Hello esteemed forum community,

first of all - a lawyer is already involved in the situation, but I would like to use your knowledge to gather additional information.

The following situation.
Our house contract runs through a general contractor.
During the construction planning, there was a so-called sampling for the equipment with a final sampling protocol.
Here we addressed an equipment and, in our opinion, it was also accepted. However, this equipment was not included as an item in the sampling protocol and we did not notice it.
There was also no additional cost for this equipment.
The mentioned equipment, however, appears one step later again in the execution drawing, which is based on the sampling protocol.

During construction, this equipment was missing contrary to the execution drawing.
Upon inquiry with the draftsman of the execution drawing, it was confirmed again in writing that this equipment was correctly specified by the planning.

For me, obviously a planning error.
The general contractor is naturally playing for time and uncertainty. For example, it is also stated in the house contract that in case of contradictions only the house contract would prevail in a graduated manner and the then additional agreements at contract conclusion. This would mean that the general contractor would have a free pass for faulty planning.
Of course, we could argue endlessly about house contract clauses here, but in my view, that makes no sense - let's keep it simple for the forum.

Therefore, the question to you.
Do you know of any rulings where planning errors from sampling to execution drawing were dealt with?

Thank you as always in advance.
Best regards

For me obviously a planning error. The general contractor is of course buying time here

So what does he want to achieve with the time in your opinion?

That the customer gives up to demand a rectification or compensation for damages here.

What exactly is it about? Is this something that can be rectified against additional costs, or is it now mainly about possible compensation?

A piece of equipment was delivered that was not approved by us in this way. Although it is missing in the approval protocol, it is present again in the subsequent execution drawing.
Correction would only be possible through a complete new production, duration about 3 months.
Compensation payment is difficult and would have to be negotiated. Correction would be preferred by us.

However, my main concern is the legal situation: missing in approval, present in execution drawing.
Have there been such cases before, and how were they decided?

Have you signed and approved the execution plans?