Something is not right here.
In 2020, you had a fairly good salary of 6000 euros with 100,000€ of equity. By now, your wife should be working again, or the unborn child back then is now 3 years old. The equity should have increased somewhat by now. Okay, a downside: cross-border commuter to Switzerland, which limits financing options.
Then: in 2021, a bungalow is planned on a hillside plot and details of the facade enlivening are already being discussed... 2, 3 months later, a floor plan is made for a bungalow on a 400sqm _planes_ plot.
Every time you explain that you come from the construction industry and know your way around here and there, so you already tell us that you can do (almost) everything yourself because you have the knowledge or have architect friends.
And then you come with a junk property (in France), which hardly has any land but has a big “provisional” beam/support in the basement and inside it looks rather lived-in and in need of renovation, but you say that you like the house and are interested.
Why don’t you choose something nicer, something affordable and yet good? Are there really problems with the financing? You were at the Sparkasse back then and received an offer... Despite the higher interest rates, something better should come out than such a disaster?! It doesn’t have to be a new building, but a affordable and well-maintained apartment should be possible, right?