Yet it sounds from these comments like it'd be faster and more people would be willing to help maintain it.

The problem there, though, is not the maintenance, it's the actual reimplementation of the thing. At this point it's probably man-years of work to do that sort of a port to a new engine, and getting that sort of commitment doesn't strike me as easier than finding one or two folks to help out.

It'd probably be far easier. Plenty of people would be willing to learn UE4 or already know it. Who wants to learn Wesnoth Markup Language?

Perhaps the cold reality is Wesnoth 2.0 will need to take radical steps away and use some rather modern engine (Unity, MonoGame, etc.) But keep in mind, right now we’re looking at a fairly successful, high production-value FOSS project. it needs short term answers as well as long term ones.