try to put a new game + (in version 0.6a this is possible) and leave only the relevant tasks as unfulfilled.
gallery #14 - when the witch is surrounded by tentacles, attack (don't use the flask)
gallery #15 - when you are securing the dildo in the second quest, then spy on the armourer before picking it up
gallery #16 - night after night peek into the brunette sister's cell, you can only progress in unlocking the gallery if you catch her with the dildo falling out of her pussy.
You have to catch her like this about 4 times