Thanks for the thoughts as always Klaus.

I'll check the sunroof drains. So far, no evidence of internal liquid water in headliner, lights, or dash.

Car is parked flat. Window is damp on the outside only. All other windows come up dry. I'll check the door drain holes.

Replaced the heater core a year ago because of anti-freeze fogging. I'm familiar with the smell and symptoms of that issue and it doesn't seem to be present here.

No load bars to interfere with door top seals. When I aggressively wash the car, I never see evidence of interior water. It only seems to happen after long term exposure, like rain.

I'll report back.