In my youth I spent much time living in on-site vans in remote places. This woman, survival Lilly, isn't an expert at anything. However I often find that these sort of content creators are better for showing what really happens. Her experience with the roof mod is pretty common place for anyone who has done such a thing. I've even known people to sell a van (caravan) without ever solving the roof leak problem. I have been contemplating putting some vents on the van we have, for those hot days and for the odd occasion that we might sleep in it. She (survival Lilly) thinks she has fixed the problem, I wouldn't be surprised if it leaks again when the conditions are right (direction of rain, force etc).