WP...
I think report does discuss this in some detail (p37-47, 87-90)... They only know water did penetrate 2 of the 3 sensors. It penetrated because it was pressure washed in contravention of the instructions. The water penetrated right into the sensors, which is not the area heated. The sensors passed the certification requirements v rain, albeit there were some comments.
Bottom line however, is the Airbus does not need these sensors to fly. Ultimately they are stall warning devices. The accident stemmed from these sensors being iced up, the crew deciding to (or at least close to) stall the aeroplane, doing so at an unsuitable height , the crew being unable to recover from the stall.
NoD