Planning of multi-family house 1200 €/m²

So the blue house actually has 3 residential units, I would also recognize the green and yellow ones as 3 residential units (even if the mansard roof visually "softens" it).

The letter from the municipality, in my feeling, leans more towards lower floor area utilization to preserve a more open building style. Therefore, I would first try to reduce the floor area ratio.
From the previous description, I gather that no basement is planned. Maybe a concept with a large apartment on the ground floor (4 rooms with garden), 2-3 smaller apartments on the upper floor (2 rooms) and again a 4-room apartment in the attic, possibly as a setback floor (penthouse), or 2x 2 rooms.

3-room apartments are lately no longer really family apartments, but apartments for well-earning couples. They might rather move to the next town. Families connected to the place or lower-earning singles with a workplace in the town would be your clientele for the 4-room and 2-room apartments. According to the argumentation, that would mean 7 parking spaces.

P.S.: Nice Porsche ;-)

How big is the largest house in the area? You should base it on that.

In §34 it states: "Within the continuously developed parts of the town, a project is permissible if it fits into the character of the immediate surroundings according to type and extent of the structural use, the construction method, and the plot area to be built upon, and the development is assured. The requirements for healthy living and working conditions must be maintained; the townscape must not be impaired."

The parking space thing was already predicted to you by . With 6 residential units, that means at least 12 parking spaces. Is there a parking space statute in the town (buyout?)

I basically agree with . I'll translate the bureaucratic speak from petulant to German, then it says: the size is okay, but create more parking spaces; the flat roof is okay, but let the third floor step back at a pseudo-eaves at the upper edge of the floor slab of the second floor, i.e. visually replicate the lower part of a mansard roof. In this mansard penthouse the picky person from the building authority wants to have an apartment – if she is single, this apartment should not be too big; depending on rank she will probably have at most A11. Call me a woman-understander ;-)

Dimensions also involve length / width. How are the plots utilized? The building authority can also see the surrounding development with dimensions in the geoportal. So can you.