My expert had no objections to the basic construction.
I basically just state this as a principle, that I do not see such solutions as the be-all and end-all. The pure doctrine must die about eight and a half times in every real-world project. I always consider it desirable – with Pareto in mind, of course – to aim to reduce it to quarter to four. But this phenomenon will probably never be eradicated completely. Nevertheless, I see no reason to capitulate and simply switch to laissez-faire, which is why I at least mention it (with the addendum that a house will not collapse on its own because of this).
What, in your opinion, would be the better solution for base insulation in monoliths?
That is a tricky matter, to be determined differently in each individual case, regularly recommending a detail drawing and not answering as a general solution. The problem mainly occurs with floor slabs (slightly less so with basement ceilings, as far as the basement belongs to the thermal envelope). Concrete is thermally problematic, which is why the floor slab is insulated. Not to forget the front edge is indeed correct. The most elegant solution would probably be to work with Isokörben (R) – but also probably the most expensive. Here I would probably choose the most efficient insulation material to minimize its thickness and thus the weakening of the load-bearing stone thickness. For this purpose, I would exceptionally saw a whole row of stones if necessary. For a wall thickness in the normal layers of caliber 365, I would probably take stones of caliber 300 here – then the base with 6 cm insulation thickness in front of the first stone layer has a half-centimeter setback. Turning the stones here and thus working with a wall thickness of caliber 248 seems borderline to me even with higher density.