Regarding the knee wall, I had made incorrect statements out of ignorance. I think you can see here that there is indeed a mini knee wall.
I measured this on the section M= 1:100, 10 cm of floor construction are already taken into account. The window position is wrong on the section! You have to go by my measured dimensions.
I think I see that on your floor plans the 1m and 2m lines could be a bit further outward?!
From the floor plans, I would like a mix of both. Maybe with ypg's suggestion, swap the shower and toilet and then move the wall a bit north, remove the closet room in the left children's room and then set up a small storage room there? I would find that useful for vacuum cleaner etc. As compensation, move the partition wall between the children's rooms a bit to the right so that a cupboard fits on the wall in the left children's room. The desk can be further to the left. The right children's room could, as compensation, receive the lower closet room from the bedroom.