Abnormal parking space regulation - legal action or ignore?

Just say who the architect is.

I am also 90% working from home. Corner in the bedroom wouldn't work for me either. But 18m² office space is usually shared by two or three people at an average employer, unless you are in the first or at least second management level, and even then the position is associated with regular meetings in that office.
So if the jobs don’t also require regular customer visits, I would reconsider priorities regarding this. Whoever has such a total budget can surely buy out 3 parking spaces?!

You don't have customer visits while working from home ;)))

That is correct, which is why 8.5 m² is enough for me despite over 80 hours per week in there. But it's not about me here... o_O

Say who the architect is.

Why? Too few words lalalalala

If you are already arguing with them, you can be almost sure that a note will be made in the files and an inspection will (eventually) be carried out. You don't even have to be at home for that. At some point, a letter will land in the mailbox.

I share that concern. Therefore, I am considering possibly not applying for the exemption at all, but instead to include the dummy parking spaces when applying for the building permit right away. The question is what "obligation" you are committing to with that and whether and how you can still get out of it if necessary.

Try Escorda’s suggestion.

I will definitely bring that to the next meeting with the construction company.

Of course that is possible. The development plan shows where it is allowed. Has the architect submitted a building inquiry regarding the changed access? At least that’s what I would have done first.

The whole thing is being planned by the general contractor’s planner. We discussed the topic of a building inquiry intensively; at first, we had planned that too. However, the planner advised us against it. The reasoning was that an informal building inquiry does not provide any security, and a formal inquiry with binding effect is actually about as time-consuming as the building permit application itself. But due to the longer lead time and summer holiday break regarding council meetings, the planned construction start would probably be delayed because the building permit might not be granted in time. We were at the building authority with the sketches, and the colleague there considered the access issue uncritical.

The recommendation was to only submit the building permit application with the garage and to apply for an exemption permit and, if this is (as expected) rejected, to draw dummy parking spaces somewhere as part of a tectur planning. According to experience, this is not checked afterwards. Whether, if it is checked after all, I could then be forced to actually build the parking spaces, or whether alternatives are still possible (such as compensation payment or legal route) could not be told to me.

That's exactly how I would do it too. If you let this be clarified in court beforehand, it can take years before you start building.