Depending on house costs and complexity, €3000-8000 are quite normal. Whether it must be submitted with the building application or even reviewed depends on the state.
So, I recently obtained several offers for single-family house static calculations including reinforcement plans. Everything ranged from €1500 to €12,000 (net prices). I then chose the cheapest one because it also had the best references.
1500€ for static calculations and reinforcement plans... You can still find many engineers who do not value their own work. What kind of hourly wage is that? 20€?
Ok. Then that's probably normal. We also have to do pile foundation... The structural analysis surely has to be submitted with the building application, right?
In NRW, I did not have to submit the structural analysis for a new roof with the building application yet. However, the documents must be with the city at the start of construction. § 68 der Bauordnung NRW explicitly requires three proofs: structural analysis, sound insulation, thermal insulation. Compliance must also be personally checked and confirmed by the planner.