Something around a year if I'm not mistaken? Also I know they stopped the train, but was there as much site work as there has been for GotG? They also didn't have to gut a building and ensure structural stability, and then re-use said shell. Or re-route a canal.
Splash is probably a better comparison, but even with just Building Code enhancements over the last 27-28 years, there is bound to an increase in build time. OSHA, ADA, and I'm sure Florida Building Code has all changed in that time as well. Each adding even just a small step in the process can lead to longer lead times for materials, designs, and construction.
Unless Disney is purposefully delaying construction for one reason or another, which I fully admit is possible (maybe you know something we don't
).