It is not "very complex." The mountain is a small steel structure. The coaster track is all prefabricated offsite. None of this is anywhere yet near a point where it is difficult or unusual for the crews involved.
Disney's Califnornia Adventure, Antartica: Empire of the Penguin and Transformers: The Ride 3-D. 'Nuff said.
I think you still need to "get it." The construction teams are going to get it done when Disney wants it done. This is not some big puzzle like you keep trying to claim where they're doing the best they can and will be done as soon as possible. It has all been planned from the beginning, from before the Seven Dwarfs Mine Coaster was back in the project. If the Fantasyland project had stayed as announced we'd be discussing the Toon Town Fair replacement and its 2014 opening. The Fantasyland project was always intended to open in phases from 2012 - 2014.