Floor plan for a 200m2 hillside house with a granny flat at

But we only build with them if we ultimately build without KFW, because for me they are too uncertain/inexperienced/nervous regarding KFW 40.

Here I would try to calculate what really comes out financially. Often the savings on energy and heating compared to KFW 55 etc. are so marginal and the effort enormous that it is not worth it.

I would also be interested in why the dimensions have to be adhered to so precisely? Is the building window really pushed to the centimeter?

Regarding the bathroom in the granny flat
Swap the toilet and washing machine
Toilet on the left exterior wall - then it should work. You have to try it out.
Are the washer/dryer only drawn in for the next tenant? It is questionable whether the work is still possible with a handicap like a walker and wheelchair.
I am still in favor of a door from your stairwell to the granny flat. It can be closed for a future tenant.