You have 3 children's rooms. So do you have three children? Are there perhaps little ones among them? Ones who might fall down the stairs? Then an open staircase that is located directly in one of the main living areas is rather unfortunate.
Is the position of the staircase in the center of the house fixed, or would you be allowed to have the staircase closer to the entrance door? If the staircase has to stay there and be separated from the main living area, this can be done if necessary with a glass wall (extending the wall between the kitchen and the hallway), then you still have enough light everywhere. But this makes the kitchen-dining area quite narrow. You can't already pass by the dining table on the left, and if there was also a wall on the right, you would be just as badly squeezed to get to the living area.
If the stair location is flexible and the staircase could therefore be on the entrance side, the bathroom on the 1st floor would have to be moved, since the staircase would be there. I would place it in the left front corner of the house and the storage room, where a window is less important, on the right wall towards the neighboring house. Where the storage room is now, together with part of the currently planned dressing room, a children's room would be created, and behind that the other. Both would have, as is fair, access to the roof terrace on the garage roof. On the 2nd floor you could leave the shower where it is, since you don’t have to keep the whole stairwell length free there, just enough so that someone coming up doesn't hit their head on the ceiling.
You have two bathrooms and an additional toilet, which is great. Most people prefer to use the bathroom on their own floor. Adults usually want only a quick shower, while children place great value on the bathtub. Perhaps the master bedroom including dressing area should therefore be swapped with the children’s room directly above. If the 1st floor becomes the children’s floor, you could take away part of the dressing room in the rear room (currently drawn as the master bedroom with dressing area) and add that space to the storage room; the washing machine would then fit there, after all, most of the laundry will be created on the children's floor.