Hmm...whatever is going on with the goblins has something to do with the accessories - even the Mansion statue no longer provides a piece ("In the next moment, when you can see again, nothing is different"), and even getting rid of all 6 rings I was wearing (blessed be the Hotel bar) did nothing. Seems more and more like a bugged-out playthrough to me.
UPD: days later, I notice a tentacle monster drop a ring, and decide to take another shot at burning the jewellery and trying the goblin painting again. Voila - it worked. How/why/when - no idea. But now Bowsette painting is locked out (black on the minimap, too). Considering I cleared the other three, as well, I still suspect the goblin painting broke somehow. Plus, waiting for a fix is pointless since the saves are incompatible between versions. F it to the moon.