Yep, is quite annoying and as soon as I have a bit of time I was also thinking of developing something in UE4 to get the data from the standard character and realtime retarget onto any character.
If you used only rotation I guess that there’s no IK, so basically is all FK data, correct?
I already used a similar setup for Perception Neuron Vive Integration ( video here ), but IK is kinda the point of doing the realtime retarget because of the precision of optical tracking.