Sound insulation VDI Guideline 4100 & DIN 4109 in prefabricated house construction

Attention, now it’s getting bizarre:

Would it be conceivable to "upgrade" the interior in a particularly "sensitive area," such as the adjoining living rooms, with a calcium silicate brick (instead of the Knauf Diamond boards)?
There are indeed two walls between the living rooms (one in each semi-detached house) and the "party wall," but only in the "case of the case": is that feasible or complete nonsense?
Of course, you lose a bit of "living space" in that case because the wall becomes thicker, but otherwise?

The "noise" or sound level of my own child is actually relatively unimportant to me personally (even in the home office); frankly, I shouldn’t have had one if I couldn’t handle it (if necessary, I currently just use headphones for Skype and that’s it).
That might possibly change during puberty, but in an emergency, there is a west-facing basement as a "retreat."

Much more important to me personally is the "decoupling" from the neighbor.
I don’t want to disturb him (after all, he pays rent!) and in the worst case, I don’t want to end up like my father, whom the "stupid sports vibrating plate" of the neighbor annoys in the basement or when the neighbor quickly runs down the stairs... God knows how often both happen.

Anyway, I’m glad there is some interest in the forum on the topic of soundproofing/standards/technical guidelines.
Who knows who else will end up here and be happy that we have already "discussed this in depth."

There is one important point I have not yet researched: the exact nature of the party wall (I don’t want to drive the provider completely crazy), I think they first need to recover briefly.

"discussed this in depth"

The "sociocultural functional quality" is

Would it be conceivable to "upgrade" the inside of a particularly "sensitive area," such as adjacent living rooms, with a sand-lime brick (instead of the Knauf Diamond boards)?

Perfect solution for you. Build a detached house

As long as you are not able to define the delivery condition, e.g., of the communal partition wall or the separation joint, we are talking a lot here in would have, could have, should have, might have.

We haven’t even scratched the surface yet.

You seem to be a friend of many words, but you convey little relevant content. What "status" does your GU deliver, how does he ensure that, what status do you imagine, and how should this be ensured in your opinion.

As long as you are not able to define the delivery condition, for example of the communal partition wall or the expansion joint, we are just talking a lot of would have, could, should.

We haven't even scratched the surface yet.

Basically, according to my understanding, the general contractor must deliver according to VDI 4100 SST II (with regard to neighboring buildings) according to the BGH ruling.

Whether SST II already represents "my personal requirement" I doubt.