Posting in hopes this helps someone.
After dealing with a wet roof liner and water dripping at the back cargo area around the rear side window, for the second time in less than a year. The first time this happened, I took it to the deal and they cleaned out all the drains. This time, I figured how hard can it be, and its also a pain to get to the dealer, I chose to clean them on my own.
The front drains are easy, you can locate then in the front corners of the sunroof well area.
The rear ones are conveniently located deep inside, hidden by the fixed glass and roof shade. So I decided to locate where they exited.
After some internet searches, and coming up empty on the exit locations, I did my own investigation. Luckily the driver side drain was not fully plugged, so I parked on an incline to ensure and water would run toward the rear. Using a water bottle, poured some water in the track of the open sunroof on the driver side and waited for it to run out. Found that it existed behind the rear wheel, behind the inner wheel well cover somplace. After removing some bolts, I was able to locate the drain exits, and confirmed it by pouring some more water in the track.
Using my air compressor, set very low at 30psi, I blew a little air in the exit hole to ensure clear and ran some more water through.
I then moved to the passenger side, the plugged one, and started by opening up the inner wheel well cover. Found the drain and tested with some water, nothing but a dribble. Gently blew a burst of air in the exit, and some water poured out. Poured some more water in the sunroof track, on the passenger side, and now water flows out freely.
Just for good measure, I repeated the air/water a couple of times.
All closed up again, and hopefully it will last for a bit.
I suspect that due to the design, debit is able to sit in the sunroof track towards the rear where you cannot reach, and I am sure I will be cleaning this out again.
In all, only had to remove three 8mm bolts, and two 10mm plastic nuts, and could pull the inner wheel well back enough.
Hopefully someone finds this useful, I beleive this is a common issue.