Water collects in left rear quarter panel cargo area and flows onto back seat carpet. How do you fix?

 

That is probably from the left rear sunroof drain tube being clogged. The best approach is to start removing the rear hatch panels back there until you find the drain tube. If I recall you can then separate it where sections join and try to clear it out with Weed Wacker Line or compressed air. Shove the line in both directions.
FYI it is almost impossible to reach the top of the drain tube at the rear of the sunroof from above.

See these threads and the first one has photos.
https://www.clublexus.com/forums/rx-...ain-tubes.html
https://www.clublexus.com/forums/rx-...-moonroof.html
and