What are the criteria for buying a house?

Stick to this clear attitude and then it will work out. You certainly need more peace than hours of searching for the best tile, heat pump, etc. In a "used" house, it is what it is, and that is often a good thing. As you can read here, no homebuyer gets exactly what they want. You always have to conform to something; you then conform to the terraced house and others to the development plan, orientation, and other requirements, and then the unknown neighborhood comes into play. It doesn't get better there, just different - Go for it!

Additional costs when buying a house are also not negligible here in Austria, of course it can be that you don’t get all of that back through a resale...

You say that it is indeed a sought-after area, ideally the increase in value over 10 years covers your incidental purchase costs. However, if the house is very "special" and located in an area where no one wants to live, resale will be difficult.
But one should rather not plan on an increase in value. All the greater the joy in 10 years.
It sounds as if you would have to move into a bigger apartment soon anyway, so living costs would increase even without buying a house, which is of course an argument in favor of buying the house.

The thread is only on page 3, and already a semi-detached house, whose construction has already begun, has become a used terraced house. What is wrong with your reading glasses?