... desire for possibly a platform staircase ... realize that first before all your other changes can even take effect. Definitely, the new draft has gained a lot of charm in the living room. I also find the dining/cooking area better laid out.
What speaks against Katja's sketches from ... there is already space for a platform staircase, and the draft really looks very similar to the last one. An island kitchen is possible. A much better designed guest bathroom. And, so far it's only a quick draft and you can still refine it. Presumably, however, the front door will have to be moved back to the right side of the plan, since a backfilling is apparently necessary and therefore steps in front of the entrance.
By the way, a door in front of the hallway does not automatically keep dirt or anything like that out. Unfavorable in the planned vestibule are the two doors, both of which open into the room. One person is already leaving the house, the next wants to get something from a room and you don’t even know where to stand in this vestibule anymore.
The last draft ... are you considering only a strip window in the kitchen area, so that the kitchen area really gets a basement feeling? Excluding south and east light there? For the kitchen, there definitely should be a proper terrace exit that is situated so you don’t always have to navigate around the dining table.
Moving the fireplace towards the dining area in the current plan, so the living room receives an entrance, makes the passage to the dining area tight, at least with such a large fireplace. You might consider separating the room right away.
For me, the bedroom would also be too narrow at 338 cm width for the bed space, at least for a house of this size. And two bathroom entrances are always somehow annoying, especially when the first friends of children stay overnight with you. And that happens quite quickly once they are 5 or 6 years old.