I'd probably try working some weed eater line down the drain before 100psi air blasts, especially if you have some blockage.
Bigger question is -- why is your sunroof glass panel leaking so badly? There are 4 drains, two front corners you can see as mentioned above with the panel slid all the way back, and two more at the rear of the trough which are difficult to see. Rears drain down the C-pillar and exit just ahead of the back tires. Is your sunroof parking in the correct location? Is the seal damaged?
If the weed eater line makes an easy exit, then it sounds like the drain tubes have come apart, deteriorated, or something and some interior disassembly work is probably in store. Or your leak is from another source.
I try to make it a point 1-2 times a year to tilt the moonroof glass up and clean the seal the best I can, then retract it and clean where it meets the surround, clean the leading edge of the seal, etc. Use either Mothers or Meguires (??) leather/vinyl/rubber product.
Can also try pouring a bottle of water into the surround when the roof is slid back and see if, how, and where it drains, then go from there.