I remember the following post, where an animated model has been placed at different positions and starts to jitter/whobble quite noticeable around 5000 units away from the world origin.
The forum contains tons of large world related posts and floating point accuracy as well as origin shifting comes up every time and then as well.
I believe, the ultimate conclusion is:
As of April 2018, there are other game engines that would be a better match for creating large worlds.