Yeah.. Engine change years into development. Though in fairness this is not that big of a deal yet also not that helpful, as lumberyard is essentially cryengine with extra amazon netcode afaik.
Right. Per comments from the devs, it was basically a rebase that between two slightly different forks, that took a couple engineers two days to accomplish. The "engine change" was effectively just a licensing matter.
I don't have a very deep knowledge of game development, but my understanding is that they moved to Amazon's Lumberyard and just went through a lawsuit with Crytek over it.