Caulk is a band-aid, not a fix, and silicon the worst. It makes a mess that will be very difficult to remove later when it starts leaking again (which it will).
A fix involves removing the vent, cleaning around the opening very thoroughly, and reinstalling with fresh butyl tape.
Given the history of "death by a thousand drips," I'd say it's time to reseal all the windows
and vents. Now's the time to do it while it's torn apart.
When you put it back together, make sure to install some support between the kitchen counter and upper cabinets. Looks like they may have been removed at some point. Scamp uses twisty metal supports at the aft end of the counter. Boler
used a post in the middle of the counter near the wall.