Yeah, the function appeared as it should have. The problem there seemed to be related that my c++ classes were not loading into Unreal at all, hence not showing in the content browser.
Once that was taken care of, it worked exactly as expected. When I reset the origin, there is no change in the DFAO and my water shaders stay put.
There is a slight hiccup, but that is a minor tradeoff for the benefit gained. Just for reference, I have a 4km terrain with probably millions of foliage instances and they all are built with mesh distance fields. And the hiccup is like, a quarter second at most.
In order to hide the hiccup, I just call the origin shift less often. Rather than doing it every time performs a certain action, I just set it on a ten minute timer because I know player can only move so far in ten minutes.