Hello,
my brief remarks on the long topic. Since there was a lot of focus on the waterproofing and the soil excavation.
Bitumen coating + dimpled membrane (waterproofing against ground moisture, load case assessment according to DIN 18533-1:2017-07 according to W1.1-E)
Waterproofing according to W1.1-E can only be done without groundwater and with well-draining soils (sand/gravel).
W1.2-E would be the use of an additional drainage even with impermeable soils without groundwater. (Here the problem is the functionality of the drainage over decades and the approval feasibility).
Black or white tank must be used for pressing water (groundwater/flood etc.) (W2.1-E).
A black tank is, as nicely quoted by Google, a thick coating by welding bitumen sheets. Of course, that is something different than a two-time coating with bitumen paint...
White tank is WU concrete. Nowadays a "grey" tank (additional joint and connection sealing on the outside) is actually used.
To assess the load case for the building, of course, the soil report is needed.
The real problem, as already described, is the seismic zone and the resulting requirements for the basement statics. As far as I know, hardly any way leads past concrete construction there.
Regarding the soil excavation, I would first keep calm. If there is a schedule, have a soil sample taken (analyses are only valid for 6 months). As of 01.08.2023 the EBV ([Ersatzbaustoffverordnung]) comes into effect, which changes a lot but essentially many things remain the same. If you have an earthworks contractor, have them tell you where they bring the material and what analysis they need. Because the acceptance points and filling companies still mostly have their old acceptance criteria (LAGA/landfill ordinance/filling guidelines etc.). This way you save yourself double analysis costs or time pressure during the excavation (analytics takes up to 2 weeks).
Regards