Two-layer masonry for residential basement on a slope - experiences?

Concrete basement with core insulation would also be conceivable.
But I would simply forget the "WDVS = evil" stories and take the pragmatic approach of the architect. You can do something against mold if it even occurs, and ultimately it is only a visual problem. It makes no sense to twist yourself (internal insulation in new buildings, stop it!) because after 10 years it would just need repainting. We are not talking about two floors but a small part of one floor, which is also very easily accessible.
Away with dogmas, sensible solutions forward!

In the worst case of lack of imagination, drawing it yourself should help: the support had to be built and secured as a staircase.

I do not lack imagination, rather understanding of what exactly is supposed to be so complicated about it. Please feel free to go into detail. Does the masonry have to have its support exactly at the terrain surface? The terrain rises about 2.5m over 10m – couldn't you then just "slide in" 0.25m thicker masonry under every meter?

I would just forget the "WDVS = evil" stories and take the pragmatic path of the architect. [...] Dogma aside, sensible solutions forward!

Yes, I think that's what it will come down to. Simply due to the lack of reasonable alternatives. Still, thanks for the encouragement!

Does the masonry have to rest exactly at the ground level?

No, it does not have to.

The ground rises about 2.5m over 10m – couldn’t you then “slide in” 0.25m thicker masonry every meter?

That would require a masonry cellar, or that it be constructed accordingly in concrete.

However, the double-shell construction would also begin stepped – and how is insulation supposed to be done below this “line”?

I consider the architect’s suggestion to make a clean cut at the height between the basement and the ground floor to be appropriate. The painter will surely find the matching color tone to the clinker for this plaster surface.

That would require a masonry basement, or that it is constructed accordingly in concrete.

Would a masonry basement for a house with a semi-exposed living basement be very unusual? I had thought that in this special case, it was the most common option. Or how is this usually done in such cases?

However, the double-shell structure would then also begin stepped - and how should it be insulated below this "line"?

With perimeter insulation. I found something on the internet (see attachment) – without knowing whether this can also be used with a stepped structure.