Yes i reproduced the problems in a very very minimal project as per your request, and i also implemented a temporal fix to the issue with shadows that probably will help to find the proper solution, since it seems like the DF is cached a way that is not gets updated upon world origin shift but only when transform the mesh (eg move or rotate a bit), in which case that individual mesh gets updated in the DF scene.
The pawn also got a sphere attached which should move with the camera, but as the video was showcasing the issue before, the camera smooth reacts very bad on World origin shifting, thus a disturbing “slide” effect will be seen when you shift the world coordinates (press 2 to see the effects of a large change).
The WPO i can confirm it is indeed does not contribute to the shadow mapping properly, which could be a missing feature of DF (it depends on how do you approach the problem), but the materials does not implement origin shifting actually, since the absolute world position will not follow the world offset, henche the color changes in the material you will witness.
The issues showcased in the videos and this repro project does not depend on WPO and user created materials, therefore the issue with DF shadows/DFAO, camera smoothing and material world position are easily reproducible individually as well.
For convenience reasons i created the repro project in 4.15 but you will see the same results in 4.16 preview as well.
[repro project in 4.15.0 launcher][1]
[1]: 137675-dfwos_ue4_15_0_launch.zip (549 KB)
ps: the trick with the visualizer/PIE was that i press the eject/possess buttons to switch between the viewports. 