Boundary construction on a non-rectangular plot (NRW)

The garage is supposed to stand about half a meter away from the boundary at the front? That seems very unusual to me.

It is apparently the case that the clearance area of the garage can only slope downwards at a 90° angle on the front side, and thereby technically exceeds the property boundary from the very first centimeter.

And where is the building window now located?

The blue line marks the building window, the white one the property boundary.

That sounds reasonable, yes. You must ensure the setback area to the street on your property, not partially on your neighbor's. Unless he agrees. If the neighbor agrees, almost anything is possible at the property boundary.

Why don't you build exactly the 3 or 5 meter distance, but instead get into the angularity? You have tons of space and potential, right?! I would align myself with the property boundary between 68 and 69 and plan a bit more freely towards the street. A boundary limits but does not oblige you to build on it. And what kind of drawn curve is that? It looks more like a traffic island curve. For me, it explains that the good lady miscalculated the few centimeters or that the house was planned quite tight already, so everything in width was fully exploited, and now the garage, which was probably planned subordinately to the house, is now extending somewhat towards the neighborhood.

There are sound, weather, and usage-related reasons why we want to close the distance on the side (west) with the garage.

If even I, usually a pretty clever guy, have slowly and drop by drop understood what the architect is strictly speaking right about, the likelihood is high that no key decision-maker will notice this before the approval stamp. Apart from pure theory, I don’t see anyone here suffering any real damage, and I don’t expect any plaintiff. Does the architect assess the problem theoretically, or with knowledge of the people involved on site? (In that case, I would submit the building application when the nitpicker is on vacation). Conclusion: theoretically, she is right (in my opinion, unfortunately is no longer active here), but it’s actually quite a long shot that anyone (who would be entitled to an objection) even notices it. Even I, who am usually rather cautious, would probably play vabanque here.

If I, usually quite the clever lad, have already very slowly and droplet-wise understood what the architect is technically right about, the likelihood is high that no crucial participant will notice this until the approval stamp. Apart from pure theory, I also don't see anyone here suffering any real damage, and I don't expect any plaintiff. Does the architect assess the problem theoretically, or with knowledge of the people involved on site? (then I would submit the building application when the nitpicker is on vacation). Conclusion: theoretically she is right (in my opinion, is unfortunately no longer active here), but it is practically a lottery that anyone (legitimately entitled to object) will notice it at all. Even I, usually more of a coward, would probably play all in here.

Thanks for the assessment! Then I better not inquire at the building authority so as not to wake sleeping dogs ;)