Structural engineer not for probation acceptance, and now?

Nobody came to us either, wouldn’t know why. The amounts of steel are specified, the site management can easily check that themselves. NRW

With us, BaWü, the structural engineer is involved in every construction phase to be concreted.

I've never heard that either. The structural engineer makes a plan, the builder gets started. With some luck, he sticks to it. Most houses don't need structural calculations (so only because it's a regulation), every builder knows how to build those inside out. It’s probably different with complex constructions. Is that the case with you?

There was no one with us. Also in BW… And our entire house is made of concrete;)

We have neither seen the structural engineer for the foundation slab nor the one for the house in person, nor were they ever on the construction site. For the foundation slab, there was a corresponding reinforcement placement plan in the structural engineering (which corresponds to a small booklet), and we all assume that it was implemented accordingly. Grounding was documented with photos.

The construction manager said that without confirmation from the structural engineer, a construction stop is imminent

Here lies the problem. How does the construction manager justify the impending construction stop - because of your refusal to accept the work or because of the missing confirmation from the structural engineer? In the first case: You can accept the work without any problem if the construction company has built according to plan. You can't really assess more anyway, and liability also remains with the construction company upon acceptance.