UE doesn’t support Dual Quaternions natively, however you can build a version with DQ support.
Link to corresponding thread, where you can ask AlienRenders, which interpolation method he is using:
https://www.daz3d.com/forums/discuss…-images-inside
Link to source code with DQ support:
https://github.com/AlienRenders/UnrealEngine
Choose 4.22 mod version in “branch” (but at first you have to register at github)