Bought an old cellar. Does it only carry wooden studs or also solid construction?

Okay, well I don't have a single structural engineer at hand since we didn't want to award the trades individually but rather build with a general contractor.
I fear that I will end up paying for structural engineering twice – first a structural engineer to calculate which houses can go on the plot + then with the construction company everything will be statically planned again for the actual house construction.

I guess you bought yourself that with this exotic plot. Mentally add it to the land price. In fact, you should have checked before the purchase whether the planned house can even be built.
As always says so nicely, straighten your crown and move on... if the project fails over two hours of structural engineering, the project probably stands on shaky ground anyway (sic!).

Exactly, a structural engineer doesn't cost the world. They look at the plans and then charge for the time. That won't be more than a three-digit amount, right?

... I rather assume that he would also like to inspect this burnt, fire-fighting water-damaged cellar in person ... plans and reality are not necessarily congruent.

I do not expect the basement to be impaired in its suitability, the fire was apparently above and "only" smoke gas and extinguishing water affect the concrete less.

... I rather assume that he would also like to inspect this burnt, fire water-damaged basement in person ... Plans and reality are not necessarily congruent.

The basement is not as bad off as it sounds now. It is dry & protected. The fire was stopped in the upper part of the ground floor. Before the purchase, we went inside with an experienced architect who looked at the whole thing and deemed it usable. But yes, if contradictory offers are now coming from the other providers or different assessments of the statics arise, I will probably still invite an independent structural engineer. But my actual question whether we should better stick to timber framing has already been indirectly answered by , since lightweight construction today probably no longer has much to do with what it used to be. So we will continue to consider both.

Lightweight construction regarding exterior walls practically no longer exists today, as far as residential buildings are concerned. However, lightweight walls indoors are literally light today because the metal profiles weigh less than the previously used timber beams – although this is partially offset again during the cladding.