Are the structural engineer costs reasonable?

Received 2 offers for approx. 190sqm, without cellar, both were between: 2500 - 3000€.

Regarding your offer: definitely too expensive!!!

170 sqm without basement

Static + thermal insulation calculation = €1,785 incl. VAT.

Local engineering office, which my construction manager regularly works with ...

20k is awful

170 sqm without basement

Structural analysis + thermal insulation calculation = €1,785 incl. VAT.

Local engineering office, with which my construction manager regularly works together...

20k is terrible

I would even say: 20K is pure rip-off! That’s actually not acceptable – unless it was unclear what was being offered....

As always, the question is what is included and what are the requirements. So only stupid answers come up.

Applying this to your request and answers:
I want to buy a new bicycle, I am 180 cm tall. The bike should cost 3000€, is that too expensive?

Answers:
- Mine cost 600€ here at the hardware store, yours is way too expensive.
- I am even 1.95 m tall and paid 1500 in a big bike shop, so yours is too expensive.
- My bike cost 4000€ even though I am only 1.65, so the price is ok.

The offers for this were all between 10,000 euros and 20,000

If the structural engineer charges normally according to HOAI, such amounts can result (see online calculators). I would call and ask what is included. There can be a (big) difference between structural engineering for the shell construction and overall structural engineering: balconies, garages, terraces, canopies, etc. If your architect planned accordingly "freely" and individually, there can be several more working hours than for the structural engineering of the shell construction.

It must be clear that dumping offers like 2T€ violate the HOAI because they are below the minimum rate, and the fee agreement is therefore invalid. The "correct" fee can also be claimed retrospectively.

"Cheap" structural engineers can also take revenge. They make life easy for themselves and add safety margins everywhere. Here a few more centimeters of concrete, there a bit more reinforcement. Then the money doesn’t go into the structural engineer’s fee but onto the contractor's bill.