Hey, after meeting the other witch and unlocking "Upside Down" I can't progress any further, is there something I'm supposed to do or is it not finished yet
Yep, it's not finished yet. I will soon add some new variations of the last scenes, as well as one new one.
So do you know how to get the Upside Down scene?
IIRC "Upside Down" happens after going through the witch's castle, and the scene should happen automatically
Is this a witch's castle?