Bungalow with gable roof, edge development, 8×17 meters

Since

I actually find all the rooms dark. Maybe that's also deceptive, for example due to the huge sofa or floor-to-ceiling windows in the children's rooms instead of wide windows with a railing.
Because of your remark about becoming part of the garden, I spontaneously had large windows, hardly any masonry on the garden side in mind.

That's true. Maybe the planning can still create more of a "greenhouse" no "conservatory" effect there.

Where is the access? Where are the neighbors?
Down in the south, is it supposed to be "reforested"?
At first glance, the corridor is way too massive....

200000 including incidental construction costs and buffer for turnkey, not shell condition?

Not turnkey. Basically, there are water connections and electrical installations.

And the train carriage story mainly refers to the hallway.

No. The service compartment for the parents, two compartments for the children, the corridor shifts at the bathroom, at the end of the carriage comes the dining room

The calculation is based on 3 existing offers, due to the "simple" floor plan, standard windows and gable roof. With realistic own contributions, including the base plate and incidental construction costs and buffer, we are currently at about 200 K.

That still sounds at best like a shell construction price.

Down in the south, are they supposed to be "reforested"?

I must have missed that (?), but something like a tree-felling boundary and as a result 40% per se not buildable would explain the 60% statement.

(The development plan states (not literally, but in essence) that the surrounding conditions do not allow any restrictions/specifications.

External links are not desired here - but if you name the municipality and the development plan number, one can google it. I think you are making reading errors here.

If there is a tree line like that, I would probably place the house there or build an angled bungalow with an opening to the SE or SW. Unfortunately, I cannot read any edge length of the property, so I cannot tell whether the garage would be better positioned further forward or perhaps in the east.

What I see is an entrance on the opposite side of the open-plan room, poor private zoning, and a hallway that, when passed through by guests and so on, immediately greets all other residents, whether they want it or not. In this respect, I would rather see the entrance in the east or rotate the house slightly so that the house can be divided into two zones. I also have a house from Danwood in mind with the two additional gables for the kitchen and living room... Here, it’s somehow just a loveless concatenation of rooms.

Is there any support from the home builder for the planning? A model house? Do they have an architect or “just” a draughtsman?

Reforested: yes unfortunately. 3 trees will still be added to the long side.

Neighbors and driveway, I'll finish a sketch again.

Wording from the development plan:

"... . The construction varies greatly in its architectural style, height development, and volume. A typical construction for the area under consideration cannot be defined. ..."