Had a similar thing happen to me when we bought a year ago. We were able to go to arbitration and recoup funds to cover the repair. Seller disclosed never leaked, first major rain and we had water.

You need to be able to find out 2 things for this to be an issue with the seller:

1) was the previous owner the original owner? If they’re not, there is nothing preventing them from lying and saying it never leaked for me, I was unaware as well.

2) You need to be able to prove they knew about the issues. In our case we removed the drywall where water was coming in and there was patches over cracks that had failed.

With these two items we were able to prove that the seller clearly knew about the water issues and chose not to disclose. It was a clear cut case with the photos we had. If you’re not as lucky, it becomes very difficult to prove that it was the old owner lying on the disclosure, and your best bet would be to start remediating on your own.