Installation appointment rescheduled because the window color is incorrect

Of course we are suffering damage; we now have to cover the foundation slab over the winter, have to remove the construction electricity/water again or else pay for them in the coming months. Furthermore, it cost us 5000 euros more to build the foundation slab on our own, and now it looks like the house will come next year (then the developer could have just built the foundation slab themselves). We have to pay rent for several more months even though according to the financing plan we should have been in the house since November. Furthermore, we are losing 10,000 euros from the KFW grant....

So double or triple bad luck. That’s just how life sometimes goes....

I consider your legal negotiating position for compensation to be weak. However, the prospect of a successful negotiation is certainly given - of course not anywhere near the full amount. Who pays for the windows at the manufacturer? Your developer? Can they get something out of it and pass it on? Compensation or a discount always have a direct impact on the result and are therefore extremely unpleasant for the developer. A free additional service can mean full value for you and does not have the same impact on the developer’s results. Consider this direction in preparing your negotiation. (Example: He paves a driveway right away, which you would otherwise have to commission elsewhere yourself.)

here is an excerpt from our contract

I can't read anything on the thumbnails. Who exactly is meant here by "Bauträger"?

"Bauträger" has settled so imprecisely for a "company that builds the house for you" like "Spot" for a light that is "round and built into a ceiling." Just give up...

Just give up...

It's not about hairsplitting for me, I just don't understand it here. Normally, the OP simply means the general contractor when they talk about a developer. That would presumably be the prefab house guy here, who only noticed the incorrect delivery of the windows just in time. But then I would be surprised if an independently hired flooring installer had more time available than one for such a major client. Hence my question (to the OP).

here is an excerpt from our contract

Did anyone recognize anything?
Then I'll put it another way, you correctly recognized that it was a mistake not to agree on a completion date with the general contractor and to include a penalty for delay in the contract.
So now you are reliant on the goodwill of the general contractor.
The approach from can certainly be tried, but as already said, no damage has occurred yet (your list has not happened yet).

Besides, the general contractor did not mess up and nowadays almost everything can be disputed away with Corona.

...as someone wrote here, it is triple bad luck.