Hello! I am the thread creator of the other thread linked here with the basement. I have also dealt with this a bit more intensively and spoken with some experts.
In my opinion: The first important thing is to assess how the water has damaged the basement, how long it has been standing there? And where does the water come from? Simply from above because the shell was left to itself?
It depends on the material, in my case, insulated stones were installed, which dry out again with perlite and regain their thermal properties. This was confirmed to me by several experts. Furthermore, it is important to watch out for frost damage.
In my case, stones were used that soak up water completely. With real frost damage, they would have burst open, you can see that.
In my case, an architect gave the green light and a structural engineer is also taking a look at it before I will definitely buy.
You have already bought, but before you put the house on it, you should consult an architect and a structural engineer who look at it on site.
An architect is liable for their planning and necessarily also has professional liability insurance.