FWIW I had a very similar problem with the front, passenger side carpet getting mysteriously soaked in my 1997 GC. It turned out to be a problem with the internal window weather seal inside the door - it had been installed incorrectly during vehicle assembly at the factory.

You might want to station somebody inside the vehicle as an observer, and then hit the vehicle hard with a hose, and see what happens.

I notice that Atlanta has had pretty heavy rain this season - more than most previous years.