The title is "Coaster Experience Speculation." Seems accurate. A lot of what we "know" is just speculation, isn't it? We're guessing about a lot. We know the Ford Anglia is involved, but we don't know that it's crashing, that's just a guess. Maybe it's rescuing us from something. Maybe it's just flying past and warning us not to go further. We don't know. We know there are pixies involved (from the poster) but we don't know how or where. We know there's a drop track section, but we don't know that devil's snare is involved, that's just a guess. We know Fluffy is involved (I think), but not what Fluffy will be doing. We are guessing that Hagrid will be in his "hut" but we don't know. We are speculating that he will be there with some Skrewts, but we don't know (though something is in there that makes fire).
We have no real idea what the "plot" of this ride is. There are several scenes that we don't know anything about. I think the ride is very far from "spoiled." Also, Merlin's beard it looks amazing!