Not to sound callous, but at a certain point, isn't this Universal's internal issue? Or specifically A&D? UOR fooled pretty much all the insiders with Transformers--if you want to track the decline of "The Spirit" on Magic, it largely began when he miffed this. For that matter, Jim Hill first truly embarrassed himself when he doubled-down on The Mouse, not UOR, having the rights to Potter. And a ton of insiders *knew* the layout of Nintendo ... until suddenly it was moving to a new park, not KZ.
Meanwhile, every HHN house has leaked before announcement as long as I've been paying attention, probably 2006 or so. I can't think of a single one that was a surprise. Usually we know the entire lineup by June. Sometimes it's almost impossibly cryptic stuff like Legacy. Other times, in the past, it was a little too easy--I'll mention him only because I consider him a friend, I think this is why Dr. Jimmy gave up after his last year of clues, he just gave it all away a bit too obviously. But I have to think if I know the line-up, any clue would be fairly obvious, especially when from a source with a track record.
I know UOR isn't shy about cracking down on rumors when they truly care. (If another prominent member on this board wants to share his story about employees showing up on his doorstep, it would show that--I myself had a similar issue with Disney earlier this year when I leaked the B&tB bar, they scoured my social media trying to find out who I am.) But it's gone on so long with HHN, it gives the impression they don't really care. Maybe they even enjoy the year-round hype their seasonal event enjoys (lets be honest, no one leaks Mardi Gras floats and bands come October). If leaks are potentially this damaging, it's on the company to reinforce to TMs that non-disclosures aren't just meaningless boilerplate, and, hate to say it, start terming TMs who don't take them seriously.
[To stress, I respect everyone I name-checked or alluded to in this post. And I've been reading speculation, contributing when I could, over a decade now. I'm as guilty as anyone in the fandom.]