Raise the living room floor level

Attached is the edit again as a better illustration of the current situation

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And, what is this drawing supposed to tell us? Everything is in order after all.

I have looked at the drawing(s) several times.
The way " " evaluated it is how I see it as well. Why?
Above the 25cm thick reinforced concrete ceiling, the continuous insulation and load distribution layer with 3.15m - 2.85m = 30cm was taken into account.
If we turn to the interior area, a 25mm (2.5cm) impact sound insulation will be sufficient due to own use, plus 4.5cm screed = 7cm freely available build-up in the interior area. Here, 2cm lightweight leveling screed, PE cover foil + 5cm cement screed would be conceivable.
Now to the exterior area:
We also have 30cm build-up height here, as I see it.
In addition to a sealing layer (approx. 3-5mm), we need 10cm thermal insulation and still have about 20cm for the top layer with leveling.
If we take a 4cm thick concrete stone in a gravel bed, about 16cm remain of the 20cm for a cover (on the insulation layer) and the gravel bed.
That’s always enough!
Therefore, I also do not understand why a large area should be filled multiple times with screed, a completely nonsensical and impractical approach from my point of view, which also touches on static aspects.
Am I maybe seeing this wrong?
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Regards: KlaRa

The problem is the energy consulting or planning, since the sloped insulation is specified as XPS with an average thickness of 20 cm, i.e. from 24 to 16 cm. With 24 cm insulation height on the house side, it naturally becomes difficult to accommodate a covering + waterproofing. But, as already mentioned, with PUR insulation it should be possible without problems to reduce the thickness so that it fits again.

In the picture, we hadn't seen any problem yet. Only with the offer from my general contractor under the item screed with 18K€ net (approx. 220sqm area) I wondered why it is so expensive. And if I didn’t completely misunderstand him, he said that due to the height difference to the terrace, several layers of screed are required.
The energy consultant also considered 6cm screed and 13cm loose insulation. Does that have such a big effect on the costs?
But I will talk again with my architect and energy consultant about using PUR insulation at the terrace to reduce the height level both outdoors and indoors and hopefully save costs that way. But that would also reduce the house’s height level; but I think with 5-10cm that might still be possible without any structural changes, right?

In the picture, we had not seen any problem yet. Only with the offer from my general contractor under the item screed with 18,000€ net (approx. 220sqm area), I wondered why it was so expensive.

The question is justified. However, the screed alone cannot account for the high amount. And why an area of 220m²?
But even with 220m² of cement screed CT25-F4-S45, this should only amount to between 7,000 and 8,000 euros.