Construction company halts work despite overpayment

Construction contract with a guaranteed fixed lump sum price

What applies here is stated in the fine print. There is no need to argue about that here or on the construction site.

I now see the problem more as one of hardened positions due to poor communication or misunderstandings.
Something must have happened on December 17 or between December 17 and the dismantling of the scaffolding that caused the contractor to act in a way that he dismantled the scaffolding. Or even earlier overall.
For the lawyer, this is of course a lucrative source of income now. Because I stick to my statement in #97... the lawyer is naturally doing his job, since he is not involved in the previous communication and behavior.
Hiding behind the supposedly "small costs" and stubbornly insisting on one’s rights, although one has already made many mistakes before signing the contract, is simply wrong. You must also differentiate: between construction defects and your own mistakes. It seems to me that now a big clean-up is being done, and from your or the lawyer’s perspective, the contractor is 100% to blame.
And if the settlement now says that you cannot insist on your fixed price regarding earthworks and the property (and spontaneous additional costs due to the soil may possibly be included... I do not know), then one will say:

Banana republic...

How did you come to hear that the main contractor is preparing for insolvency? Is he perhaps just threatening with it? I’m also a bit surprised at how he could so quickly establish a new company in the same industry? That should usually be difficult unless he has 5 adult children and a wife. If the insolvency really happens, I see little chance that this company will continue to be involved in the construction. If you are lucky, there will be an amicable agreement on who will continue the construction and the damage will be distributed somewhat among all parties.

If the construction company suddenly realizes after completion of the shell of the ground floor that the ground floor should have been built differently to support the load of the roof structure and then has to build walls differently in the attic because no execution planning was done,

that due to the static calculations, massive walls would now have to be built in the attic instead of drywall.

This sounds particularly strange when considered together – does the general contractor have any expertise at all?
In the attic, it is usually the other way around, i.e., switching from masonry to lightweight walls; static reasons should actually only apply to load-bearing walls; to me, this rather sounds like a change from a beam roof to a rafter roof, and also not dependent on the ground floor (I would have rather believed that if the ring beam had actually been omitted there). The choice of wall material in the attic is usually made before the preliminary planning.

How did you hear that the general contractor is preparing for insolvency?

Insolvency is not an optional choice – there are criteria for it, and they are either met or not. Therefore, he would have to prepare the fact of insolvency, which would, however, be an insolvency law offense.

ER is a GmbH, that's true.

Are you sure? When I browse through your thread history, there is a post where you inquire about a BU from Leipzig-Taucha. However, this is a sole proprietorship (e.K.). That would make the insolvency speculation (although it remains to be clarified where that comes from) rather unlikely, since the owner is known to be fully liable with his entire private assets.

The intermediary is a sole proprietorship, the executing BU is a GmbH with one person.

I know the planner commissioned by BU; he has expressed himself to her regarding the insolvency. She has also been receiving hardly any planning orders from him for some time now. The intermediary is giving up his business at the end of the year for age-related reasons. As far as I know, BU is supposed to take over this.