Those holes are from factory covered with black tape preventing water to enter. Most 2cvs take in water from either the wiper spindles or the air vent seal. 9 out of 10 the spindles are leaking and need replacement. When the seal is not sealing, it need to be removed possible replaced including the holding strip. If one of the studs are missing, water will find its way in. Last thing to do is to fit a foam seal similar to door and window antidraft seals found at hardware stores (also used on the flipping side windows) Very rarely does water enter around the windscreen seal.