Just keeping abreast of my discoveries as I try to progress:
1. Seems like the staircase in the Charms classroom is glitched, have the journalism quest and click to go upstairs, but you just get reset into the Charms room.
2. After doing the second part of the ghoul mischief quest, the polyjuice one, I get a hard crash. No floating through the universe, just gray wavy screen. I used Unstuck, and it just stayed on the gray screen.
Can confirm that the codes above fixed the problem with the Advanced Charms II quest though! Hit that glitch again and was able to progress through further, until I got stuck on the gray screen after the Slytherin adventures.
Weird note though, while Polyjuiced the control scheme changed from what it was set to for some reason. I was using the 'face the way you move your mouse' method, and suddenly it was just pure WASD.