I was thinking the same thing how is water getting into these places? I see a lot of posts about standing water in very bad places like modules and audio equipment. I'm going to take a shot in the dark being most of this stuff is in the rear.
With that said I would check the the rear door hatch weather stripping and seals and look for any obvious sign of rips, tearing, dry rot or punctures.
If not there I would start checking inside where you found the water and try to ascertain which direction the water came from. I would check the wheel wells see if any of the partitions are cracked or missing may have to check behind them as well.
There is another possibility but this is a real shot in the dark being I'm unsure how solid or hollow the upper frame is.
Perhaps the panoramic moon roof has a seal/weather sripping problem and water just finds it's way to the lowest point channeling through the body/frame of the vehicle.
All of this is a sheer guess as I have not have an issue with this thank god.. or at least yet lol Maybe more experienced member will respond with common breach locations. For now if it were me that's where I would start looking.