I dunno know-at least on ours, the internal door swings freely inside of the vent housing 'snout' that protrudes thru hole in camper wall. Nothing about it would give the slightest resistance to water entering.
However on ours, indeed water wouldn't get into hood, water getting past outer door would run down inside of wall. The snout of outside cover and the hoods snout are not connected or sealed to each other. Our Ventline is worse than some due to its the small opening style the goes thru wall. Uses same outside cover (and hole thru wall) that is a lot larger.

