Developer refuses to hand over documents

Also don't get me wrong. But I really don't see any problems here. As long as the walls are properly anchored, the holes are absolutely not a defect. It depends on the plasterer whose task it is to close these and then plaster the walls flush. Sure, it's something else that's nice. But defects? None can be seen based on the pictures.

But he recently said that he has never been on the internet

Boris can show him - he was already online with AOL earlier than I was back then with T-Online
But maybe Mr. Hoeneß is just mistaken here: my "father-in-law" once proudly showed me that he didn’t need an internet connection at all, since it was completely enough for him to just go to the WWW instead (thanks to WLAN he doesn’t see any "cable" to his tablet). Westphalian. Before I cleared up that mistake for him, I myself grew old and gray

Great bricklayers, although this is certainly not their profession.
Picture 1: Not nice, but you can still close with stones.
Picture 2: Botched job - Front part is no longer a wall but a pillar, which would also have to be proven accordingly. This part was probably patched later. Wall ties are definitely not present.
Picture 3: Wall ties are missing, so defect.

If you look at the photos and the site manager does nothing about it, you cannot expect anything better for the rest of the house.