Thermal bricks / Poroton and insulated clinker - Is that optimal?

Good sound insulation is provided by building materials with high density.

All building materials have poor sound insulation if there are incorrect connections to other components.

The perfect wall construction for me would be: sand-lime brick - mineral wool - facing brickwork.

Building with a cavity wall is also what I consider the best in terms of quality. However, I would not use mineral wool as insulation. It only has idealistic advantages over EPS and otherwise only disadvantages. Especially price and susceptibility to moisture.

I wanted it to be more vapor permeable to the outside, which is difficult with EPS, but no problem with mineral wool. So far, our insulation layer is dry, so I don’t expect any problems *touch wood*

Theoretically, I would agree with you on the two-shell wall structure. Unfortunately, it is probably the case that construction errors occur much more frequently with two-shell structures, and the additional costs should not be underestimated. In the two-shell variant, I would choose Thermoziegel, PUR, brick.