Mmh, so we have been living here for a year now and I can't say I would do much differently.
For the planning of the technology, maybe trust a [TGA planner]. Some things could have been done more cleverly. We built with an architect. Planning the technology is not one of their favorite tasks. And the craftsmen themselves rarely see the overall concept.
In the execution, I would pay more attention to some details. For example, with open construction methods, you should think about sound. And the solid 17.5 cm wall is useless if the room door is installed with a 1 cm gap at the bottom and the frame was foamed in spots, but there is a 2 cm gap all around the door opening.
Just the other day, I stuffed this cavity of a door with insulating wool. I can already notice a difference.
So far, I wouldn't change the floor plan. Maybe two more windows. But that's hypothetical because if I were to build again, it would be on a different plot and then a different floor plan would result.