A few things I would reconsider:
The wardrobe cupboard will not be sufficient for 4 people even with a depth of 60 cm, and you are planning:
A little space for coats is still under the stairs,
However, I would not find the view from the dining table to the front door and the stairs as well as the things standing around underneath nice. That is why I tried in my idea to avoid exactly this (line of) sight. You could also simply make a door to the living-dining room, then of course you would not see anything or not so much anymore.
I find the sofa with the TV looks very cramped there. But if you don't place much value on the living room and don’t have a big TV, it fits.
Upstairs, the children’s room on the left side of the plan is not nicely furnished, in my opinion. The bed is uncomfortably positioned with a view of the door. You would rather want that on the wall facing the office. Then the window would have to be moved outward again.
If the children are supposed to have access to the parents’ bathroom anyway, I would consider eliminating the small shower bathroom entirely. I also don’t think you need 2 toilets upstairs if there is still one directly down the stairs. That would have the advantage that you would have space for a dressing room and/or a larger bathroom.