I have read all 10 pages. It is really hard to understand who does what and where. You immediately put clear terms like developer, contractor, and construction company into play and then turn their meanings upside down two pages later. That doesn't work.
Since you are the owner of your property, no developer can be involved here (developers sell the finished house with the land).
So what exactly is a construction company and what is a construction firm? They are basically the same, aren't they?
Who do you have a contract with? Very likely a construction company, where you ordered a "turnkey" house.
The construction company hired a subcontractor (construction firm) who took over the masonry work.
The construction company with which you ordered a turnkey house has now filed for bankruptcy?
Is that all correct so far?
It is good that you basically have "paid nothing" yet for your shell construction there. The floor slab didn’t come, of course, because the construction company did not pay for the previous slabs anymore (bankruptcy). The payment plan has been extremely accommodating to you here, otherwise you would have lost a lot more money.
With the severe defects, the work already done is naturally not worth much. However, you already know that you can also insulate the base/floor from above. But I would still have the upper floor raised as a precaution. In the very unlikely event that you don’t need this extra height, you’ll have higher ceiling space later. But if you do need the height, you’ll be living in a cave later. At this moment, that’s a joke.
However, much more important is how you get out of the contract with the insolvent construction company. The administrator will certainly want to collect money for work already done. Whether he releases you from the contract and/or still demands defect repairs or can drag the whole thing out will certainly be best explained to you by your lawyer.
The best thing will probably be if you get completely out of it quickly (without defect correction) and don’t have to pay a cent for the botched work.
Then you can either hire trades one by one yourself or look for another company to finish the job. Both are not easy, of course, because no one wants to take responsibility/warranty for the current botched work (after all, the foundation of the house).
You need a proper expert who specializes in foundations/base slabs. Whoever omits the perimeter insulation may also make other mistakes...