I would have your own inspector review, but generally if you have the warranty and can see the paper trail, I'd be much happier knowing that this was handled right than having to do this work myself. Most homes in this area have some water infiltration issue, whether past, present, or future. So either you are going to take care of this or someone before you did.
The high water table is pretty much bs IMO. For flood insurance, you can get copies of the maps on the federal web site, but if you need it you would know (i.e. you wouldn't have been able to close.)