Floor plan design - two options - single-family house 166 sqm

Yes, and to get to the living room, you even have to go down the stairs :D

But you don't have to rush to the living room. When your bladder calls at night, the way is too long! That time comes sooner than you think.
Bedroom, I see a south-facing window: I would omit that. It only brings heat or draft.

Do you think the 45 sqm living/dining/kitchen area is sufficient?

That's sufficient. What personally bothers me: always through the living room if you want to go to the kitchen and pantry. That degrades the quiet area to a busy passage room.
Is the bottom of the plan west? I would put the garage on the other side. West would be sacred to me as a light source. In summer, the sun sets in the NW!
Maybe the rooms should be rearranged after all?

after intensive engagement with our ideas and our room program, we found an architect who implemented these ideas for us.

That doesn't have to be a blessing. Just as in medical training the content of delivering bad news is often neglected, it seems that in architectural training explaining away Pinterest castles is also lacking :-(

A completely different house! Apart from the long way to the bathroom, which has already been criticized, the way to the kitchen is also far. If you swap cooking and living, you could use the storage/airlock as a pantry, have a nice long wall in the kitchen, and overall more space for the island (with 3 children, the kitchen would otherwise be too small for me).

The walking paths are simply complicated everywhere due to the staircase core in the center. When I look at how to get the groceries from the entrance to the pantry, I also see a zigzag that would make me curse the architect by the third time at the latest. Traditionally, such houses in the USA (at this size, so not Tara or Twelve Oaks) have a straight long staircase along which a long hallway runs.

Thank you very much for your input. We have taken this as an opportunity to fundamentally reconsider the plans and to sit down again with the [architect].

to fundamentally deal with the plans again and to sit down with the architect again...

Significantly downgrade the appearance if the result is not supposed to be more than a quantum leap.