Rough estimate of renovation effort / costs

I had read, however, that in the 70s the thermal insulation was not yet so optimal

What thermal insulation? :D There was basically none. Stone and done. Okay, different stones, but... You surely don’t live in the same rental apartment for 20 years, do you? Have you never felt the wall temperature of the exterior walls in winter? In your own apartment, at friends’, acquaintances’, parents’, etc.? Where do the houses actually "live"? You keep coming up with "new" ones all the time.

What thermal insulation? :D There was practically none. Stone and done. Ok, different stones, but…

You surely don’t live in the same rental apartment for 20 years, do you? Have you never felt the wall temperature of the exterior walls in winter? In your own apartment, at friends’, acquaintances’, parents’, etc.?

Where do the houses actually “live”? You always come up with “new” ones.

The houses live in the far southwest

again regarding the mid-terrace house built in 1995 the garden (that's the house with the stains in the basement :)): regarding the basement I will make an appointment with an expert. He can then possibly also look at the rest and give an impression of the condition of the property. The realtor also offered me that he has someone who can do it cheaply, but I think I prefer to take someone independent, I think that's more neutral, but it also costs a few hundred euros.

And then another question. Switch to semi-detached house built in 1978: what does final energy consumption mean....is that the total value even after deducting solar heat generation?

The family tends towards the mid-terrace house. I would have preferred the garden and the double garage, but in terms of location, the mid-terrace house is better, it's also a bit cheaper, although that wouldn't be the deciding factor in the end. Now it would of course be good if the neighborhood fits as well. With terraced houses, you are quite close together. Unfortunately, you only notice that once you have the house.

How much would one have to budget for the following renovation/repair work? About 110 sqm of parquet (can be relatively simple), of which about 85 sqm is carpet that needs to be removed, and painting all the walls. Thank you very much in advance