New construction cost calculation, suitable for architect?

We received a good recommendation from another builder that the costs calculated were adhered to. Architect is LPH 1-8.

Firstly, I believe, secondly and thirdly do not match the delta between his estimates and what the experienced fellow discussants know as reality.

We are currently building 185sqm living space clinker brick with a gable roof and the costs for the basement 300+400 are approximately €2,500/sqm. I know this does not fit the worldview here, but these are the actual costs that have been incurred or are currently being paid.

So does your experience align with the architect's estimate?

Are KG300 + 400 the trades I listed?
I searched and it should match with the trades and KG300 + 400.

So does your experience match the architect's estimate?

I currently have clients on the table who are building for almost €4,000. So what now? Professional clients (property developers, general contractors, project developers) usually calculate roughly €3,500/sqm for the 300/400 costs.

When I see the cost breakdown, I feel sick.

Interior and exterior plastering 75,000 euros.
Heating 50,000 euros.
Windows 52,000 euros.

Architect fees 82,500 euros.

Just the costs for plastering alone. Let's generously estimate 500 sqm of area to be plastered. That would be 150 euros per square meter.
That is at least 3 to 4 times the usual price. Any normal specialist company would do that for 20,000 euros.

The floor height 3.50! Is this going to be a palace? Why not simply 2.50m? Money obviously plays no role.

My first requested general contractor has a price of €2,550 / sqm turnkey.

Architect cubic volume calculation
Cubic volume:
Ground floor 3.35m
Gravel 0.3m
Base slab 0.3m
Shell construction height 2.75m

Upper floor 3.5m
Ceiling above ground floor 0.25m
Shell construction 2.75m
Ceiling above upper floor 0.25m
Insulation 0.25m

No castle, only 2.75m shell construction height.