Development plan with eaves height 3.5m and wall height 6.5m - what applies?

But you don't build three meters lower just because the development plan "speaks unclearly".

The question is also whether the city villa is even permissible. Or whether the BP doesn't block the second full floor anyway.

The question is also whether the city villa is even permissible. Or whether the building authority won't block the second full floor anyway

I don't think so, with 9m ridge height and 6.5m wall height, I don't see an anstattvilla as impossible. Maybe it is supposed to have a "mansard roof" fake eaves (that would fit with the gutter lying three meters lower). Very strange, but unfortunately the original poster is in no hurry to clarify ...

No answer (from the OP) is also an answer. The whole thing sounds like a development plan on a slope, where the OP may have mixed up the references.