A few users successfully reported to being able to use the plugin with Rokoko mocap animations. Below a few references.

Review by robahj on July 12, 2022 11:05 AM:

saving me hours of time
[…]
I use a rokoko mocap system and posing characters manually through rotation (especially to retarget accurate finger data) was taking up DAYS worth of time. that's if I got lucky and the retarget pose editor didn't bug out on me.

I am exporting my rokoko skeleton as a mixamo asset and using this plugin to quickly retarget to my custom character (using same hierarcy as the Ue4 maneq) doing a bit more research on the generating root motion side of this plugin as the rokoko studio does not export root motion data either, so this would be exceptionally handy to figure out so I do not need to add additional root bones mapped to pelvis movement.

super handy plugin that I needed right now[…]

From our Discord server:

[…]I've just made a quick test exporting one of the sample animations from Rokoko. In my case the exported fbx had the strange pelvis rotation, but running it through our retargeting plugin fixes it.