Just a brief note to close this topic. This house was subject to a [Teilungsversteigerung], which was then canceled a few days before. No reasons were given for this.
Therefore, unfortunately, I had no documents for the house and could not speak with the previous owner. But it was resolved anyway.
Has anyone ever had experience with such an auction (negative or positive) or maybe acquired their own home through one?
I have to say, even if the auction had not been canceled, it would have been really too risky for me in the end. Too many uncertainties/risks, etc.