With thinking through about it, I have more of what I would personally want to see out of a Forbidden Forest expansion..
To explain the Great Hall and the E-Ticket..
Great Hall
To explain why I placed the entrance/exits of the Great Hall away from Hogwarts is very simple and in a few ways..
A.) In Deathly Hallows part two, it is showcased in a scene that there were at a time before Deathly Hallows multiple passageway's that led from Hogsmeade to Hogwarts. It can be purely explained as simply put, they needed to find a way to bring people to Hogwarts with more ease without going to the castle itself from the FJ entrance; so, they use the passageway's to allow them to travel to the castle with not that many issues
B.) It'd be a situation like Carkitt Market. They simply would need to just have the entrance to the dining experience without having it all at one situated location; and that it could potentially add a bit more little lore to the Wizarding world in a sense of adding more to the Forbidden Forest; just like how the Market has done that for Diagon Alley.
As for the experience, I'd say it'd be like a dinner-experience on the vein of a Dinner theater experience with various acts exclusive to the experience as apart of it; allowing changes for various periods of the year (Halloween, Christmas, Valentines Day, E.T.C.) while offering somewhat of a higher quality of meals and drinks that are all inclusive to the experience when reserved to divulge in. It'd be a high end experience that would be a one-of-a-kind type offering that Universal Orlando can pull off for the park.
The Dark Forest E-Ticket
This one, is more easier for me than anything.
It'd feature a high-octane indoor/outdoor thrill-coaster with the ride vehicles being based off of Ford Angelica's with it being an attraction that is on the scale of thrill similar to Big Grizzly Mountain and Expedition Everest with interactions with the area surrounding it along with it being a mixture of a terrain coaster (artificially) and an inversion coaster that has multiple launches throughout.
It'd be either a Mack Mega coaster with custom trains, a Gerstlauer Family coaster (in the track and trains) or something similar to what Vekoma has done at Disney.
It'd also be a coaster that reuses concepts unused from the Japanese Dark Forest concept that was canceled with new features along the way from it, culminating in a brand new E-Ticket attraction for the area.
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While this isn't my best, it's a quick one that I wanted to bring out..