I went searching through the edit histories of the LBT 14 page and of the actors/actress selected and I found some odd things, although still no evidence to make me realistically consider this authentic.
The page was originally created by a wikipedia user named Scratte2, who according to wikipedia doesn't actually exist (I'm not quite sure what to make of that, considering he does have an edit history). I looked through a few other edits to other pages this user has done and what I found has been the largest piece of evidence against this claim of a new movie. The user has done a few very small edits on other pages, all edits of which were quickly removed by other users, suggesting that this user isn't very reliable. The LBT 14 page its self has had two other users edit it. One put up some obviously fake plot story about Jesus coming down and telling everybody their going to be extinct, blah blah blah. The final editor removed the fake Jesus story. No one else has touched the page.
As for the actors/actress as of last night every one of them has a reference to their supposed part in LBT 14 except for Jim Cummings (Supposedly voicing Petrie). Jordan Nagai (Littlefoot) had LBT 14 added to his page yesterday by the user Gran2. From what I can tell Gran2 does not seem like someone who spends his time playing jokes, he is a very active member and a large player in the Simpsons wiki. For the other actors I found something VERY bizarre. Their pages were all altered by a single person (I'll refer to him/her as 67 since thats the first two digits of his IP address). Now the weird part of this is that 67 altered them on November 15th while the LBT 14 page wasn't created until November 28th.
I still don't have a reason to believe this claim but if it is a hoax, it is a rather strange one. I'm still not quite sure what to make of it, but don't get you're hopes up, there is still no reason to believe in this.