What you experience is normal, and what happens to all of us.
There are differences in how "hard" a wing will ventilate, but yours is quite good at keeping lift, and can sometime regain after ventilation because of its sheer size - but other times it will "drop" you.
When you get more experienced, two things will happen (without you knowing, it simply takes a lot of time):
1. You will NOT get the tip or wing over the surface, not even in chop, very often.
2. When you do, you will be able to ride it out, more and more often.
But you will still, even when really experienced, get some radical wipeouts because of ventilation - it is just a part of the game that will happen now and then when you push it to the limit
Yes, on some videos (especially the Ketos, Pink Lady at 1:48
) you can see part of the wing over the surface - this is a "stunt" so to speak, because she has good control, and can keep the rest of the wing stable under the water, using the lower part of the mast as a wing too while leaned over, and using the kite to get sufficient lift.
With raceboards you lean over too, and really powered, so here you can also ride like this often.
But when not having lift from the kite, and more upright, it is way more critical and you will often drop fast...
In short, all main wings might drop you hard when you ventilate, a bit different how rapidly they do it or regain, some are A LOT worse than yours, and a few might be better - but it is just how it is with all of them