Hi Jesper,
it seems to be a miracle! Can´t you find any wet areas on your carpet? May be, it´s helpfully to lift them all up.

I think, there must be humidity in the cabin.

May be, the water drain passages of the sliding roof are choked or there is a leak in cause of rust at your windshield (rust between the windshield seal and the body).

As the recirc flap is working proberbly an the heater circular hasn´t any leaks, ther must be water draining somewhere into the cabin.

Beste Grüße
Tim