House purchase - Water damage assessment

I say: fairy tale hour seller. The story is completely incoherent.

let it be measured, otherwise ask a professional what sealing from the outside would cost in the worst case

has it also rained in the last few days? If yes, then the things should be wet now.

Buying the house wouldn’t stop me from doing it if everything else is as you say. If it has been dry currently and apparently for years, then the matter is settled and not a problem.

What kind of pipe is that anyway? Are you talking about a downpipe? Gutter?
The 'damage' visible in the picture looks like dirty water once ran down the wall.
In my opinion, that also fits the seller’s story.

it should have been a concrete basement in 1994.

Consult a building surveyor, possibly one who specializes in the topic of [Bauwerksabdichtung]. If you like 95% of the house and it hinges on the corner, I would put that into perspective and seek detailed advice. Think positively.

Hey,

Right, that is the downspout from the gutter. We will pay attention to freshly entered water during the next visit and contact an expert.

Thank you for your responses.

So what’s weird is that the basement looks very well maintained. In the pictures, it looks like the walls were painted recently? Still, there are stains. If the house is otherwise fine and the price is okay, negotiate the costs for excavation and sealing and deduct them from the purchase price.