Can the move-in be postponed due to defect remediation by BT?

Good day. I would like to know the following. Is the developer allowed to postpone the move-in date communicated by email (we have terminated our apartment based on this) to the original move-in date according to the purchase contract (which is 2 months later) by remedying the following defects? During the preliminary acceptance/inspection of defects by the owners (i.e., without an expert), minor defects (cosmetic flaws) were found. These were fixed by the time of handover, but we are bringing an expert to the handover (we are allowed to bring one) who will surely find more defects. Is the developer then allowed to refuse us move-in (because they still have to fix more defects)? Or does it depend on which defects are found? What if our expert finds defects in the common property? What if he finds defects in the individual property? For which defects can he refuse us move-in? For which not? Thank you!

What exactly does your contract say? Every BT has its own individual clause that relates to the acceptance.

The contract specifies a handover date with a note about a possible earlier acceptance. This earlier date now seems to be occurring. The new date (2 months earlier) was communicated to all owners by email. The property manager assumes a smooth handover. However, since we are not allowed to bring an expert for the inspection of defects before the handover, I now fear that the handover could be delayed if our expert still finds defects at the handover... For the inspection of defects 2 weeks before the handover, we are not allowed to bring an expert. And not all owners are experts...

The appointment 2 weeks prior was voluntary (see another thread). You can always bring an expert (how could he legally prevent that, you can go there with whoever you want), but the company will probably not listen to him much. You can also go look at the construction site with an expert at any time (if you have a key). An expert does not have X-ray eyes and can only see what is obvious. He cannot see the botched work inside the wall, and you don’t call in a specialist for a few badly hanging wallpapers. Ultimately, you can bring a specialist during the handover, but that is actually much too late. He cannot see whether the underfloor heating is installed properly, he cannot see whether the sealing of the welded membranes at the window was done correctly, he cannot tell if a corner is properly insulated, if all pipes are tight, and so on... He basically only sees what anyone with some expertise can recognize (whether the heating works, whether floor/wall coverings are according to the contract, etc.)

The moving-in date can be postponed by the builder if necessary. Surely there is a clause in the contract for that. With a regular construction company, there would be no problems because you can do whatever you want with your property (which in turn could have other legal consequences).

I don't believe you are allowed to bring someone onto a BT construction site, it is not your property.

Until handover and payment (subject to other contractual agreements) the object remains the property of BT.

That is why it is also unlikely that the TE already has a key.

As I already wrote in the first sentence, this preliminary acceptance is purely voluntary by the buyer. Of course, you can bring anyone you want to the handover. When do you actually pay the installments to a developer? Surely not 100% upon handover? What happens if the company goes bankrupt beforehand?! Is there any legal protection or do you have to file a claim in the insolvency estate and end up ruined?