by KarasuG
Essentially, yes; the Haunt table is mostly a result of tracking trigger omens/rooms, and distributing each Haunt to which combinations either offer balance or make sense in the story.For example, Haunt 15, Here There Be Dragons, is triggered by the Spear, in rooms related to heat/fire (Charred Room and Furnace Room), as well as two other rooms that weren't needed for other Haunts (Gallery and Servants' Quarters). By contrast, Haunt 48, Stacked Like Cordwood, is triggered by combinations that were otherwise unused at all (Mask + Charred Room, and Spirit Board + 3 separate rooms). #48 is one of the few Haunts that holds absolutely no relation to any specific omen or room.
I know there are definitely resources out there for fan-created Haunts (a quick Google search lists several of my favorites), and it's not that hard to rearrange the Haunt table to accommodate everything.
http://www.mindflare.com/betrayal/ is the most well-written and detailed source, since the author also included advice on Haunt design and balance, as well as two of his own Haunt tables (one for his own haunts only, and the other for his own + the official Haunts). I've spoken to him through e-mail about some of his creations and about the game in general, and he's quite friendly and helpful. He did write everything for the original 2004 version of the game, and two of his Haunts are actually *in* the second edition, but I don't see anything that would stop the rest from being playable in the new version.