Damaged roof window in shell construction

Hello,
we have purchased a condominium that is currently in shell construction. Attached is the photo of the damaged window.

My letter to the developer:

"Unfortunately, I have noticed that the roof window in the bathroom is damaged. It is not just a scratch, but the frame is damaged so that one can see 'the interior.'

Since the effects on durability and possible problems cannot be assessed, I assume that the window will still need to be replaced."

The response:

"The executing company has filled the damage with liquid plastic; the double casement window will not be replaced because of the damage.
It can be absolutely excluded that the damage impairs durability or the like.

The damage is behind the drywall to be installed and also causes no disadvantages there."

How would you deal with this?

I would at least negotiate a discount. It is definitely a visual defect since the damage is exactly within the visible area. If they do not agree to that, I would insist on a replacement.

So, if the whole thing was really repaired accordingly with liquid plastic, then a replacement is hardly feasible. That would be anything but proportional. Of course, one assumes I buy new, so also undamaged. But there will hardly be more than a small price reduction, and I consider even that unlikely.

The developer also communicates this, and since it is not visible but hidden behind the drywall, I also see it as unlikely. Even though I understand the hassle, factually you do not incur any damage, provided it was properly repaired. I would possibly have that confirmed, but you probably won’t "get" much more here.

This is not a visual defect. You can't even see it when it's finished. Replacement is not reasonable. Liquid plastic is sufficient. Take photos and have it recorded in the handover protocol later.

Well, I don’t see anything else there either, not even a discount.

if it is not visible later, then of course no discount either