I will most liekely use your doors idea for the next game.
Chaninging physics so late in development is almost impossible it would change too many situations.The idea with the equally hight wall is very good. I thought that I softlocked the players enough at that point but it seems they have to be softlocked a bit more. The only problem is that you need to run over the water for the secret so the gap would be a problem. The easiest solution would be to make the water deeper but that would still be much work. Resizing the room changing the map etc. and I am not sure if it would work because one player got stuck at a similar point where the water was much deeper. But I will try that solution later. A few days ago I would have instantly tried all of this solutions but at the moment I am a bit overburdening myself. I am already thinking of more or less closing the bugreport thread and to prioritize my next project.
But I am impressed, I can see that you are very talented at problem solving. Most people only tell me what they don't like but don't really tell me realistic options to make things better. Maybe if I some day need help with Bobo 2 I will ask you.