Positioning of the house on a north plot

The house is not yet fully planned, but of course there is already a certain, indeed relatively concrete idea in mind. And that there are larger window areas in the living-dining area, I think, is not so unusual.

And that there are larger window areas in the living-dining area is, I think, not so unusual

A house is known to have at least 4 exterior walls, so it is often the case that the windows extend over 3 exterior walls. Either there is a specific one, then please upload the design with the fixed windows or be open to window shifts in the design. If there is tunnel vision regarding "only one window front": it doesn't matter, the forum is there to correct one's own limits and barriers, so that it can be done differently :) It can't be that suggestions are made while keeping all the house possibilities in mind, but you refer only to one that is not revealed to the forum.

In the layout we currently favor, the living-dining area would be in the northwest. There would also be larger window areas there. But there is not yet a concrete, ready-to-build design. We have just started the discussions ;)

However, we are unsure whether the building line can simply be circumvented in this way

I do not believe this is approval-worthy because building parts retreat to more than a minor extent. Since building lines require a special explanation in the reasoning of the development plan, knowledge of this could shake or confirm my belief.

Would it be possible to place the house at 10 and the garage at 7 directly adjacent? Or would a garage also have to be on the building line? This building line is driving me crazy.

Would it be possible to place the house on 10 and the garage on 7 directly adjacent?

I don't know.

Or would a garage also have to be on the building line?

With strict application of the Building Code and Land Use Ordinance, yes, but ...

This building line is driving me crazy.

Completely justified. Setting a building line there is urban planning madness and the reasoning behind it is a joke: ... This specification serves to integrate into the immediate surroundings of the buildings, which on Bahnhofstraße complete the direct gap closure of this inner area development. Nothing more! Meanwhile, the house bordering the building area to the west does not even stand at a 5m distance from the street. If the building permit approvers have as little understanding for the city planners as I do, your plan from #1 might still get approved.