Offer for Frisian house with garage, okay?

Besides the obligatory costs such as incidental construction costs, pattern inspection, additional earthworks, painting and flooring, etc., the crux seems to lie in the following passage:

Dazu kämen dann noch Kosten für Statik, Bodengutachten, Anschlüsse, Architekt etc.

In particular, the costs for structural engineering (by which I do not mean the pure calculation, but the additional execution costs incurred due to the structural engineering) can turn out to be a surprise package.

Sockets etc. are already more extensive than in most other offers. The air-water heat pump is a high-quality branded system that is precisely calibrated. It is contractually agreed. Construction electricity and water will be provided, but consumption is billed separately. Earthworks are included.

Why remove solar thermal? It absolutely makes sense for hot water!?

Besides the obligatory costs such as ancillary construction costs, patterning, additional earthworks, painting, and flooring etc., the crux seems to lie in the following passage:

In particular, the costs for structural engineering (by which I don’t mean the pure calculation, but the extra costs in execution that come with the structural engineering) can turn out to be a lottery.

The contract explicitly states that the execution will be carried out according to the structural engineering specifications. So it is included in the price and therefore no surprises.

Earthworks are included.

Included removal, no matter how much it actually ends up being? Or rather only x cm in the area of the foundation slab?

How is the architect paid? According to the fee schedule?

The architect has already submitted his offer and will be charged according to the minimum rates of the HOAI less his discount. But that also does not matter, as this is purely about the offer from the GU. Disposal of the soil is not included, as the excavation is needed for backfilling and for the terrace.

Well, it does matter because normally the architect's service is included in the [GU offer]. And if it is not included for you, it must be taken into account in the calculation. Otherwise, comparability is simply not possible.

Structural engineering, architect, soil survey are included in the [GU offer] in my case (and in many others). That, of course, makes a difference in cost.