Mirroring a character's pose inside sequencer (why is it so hard?)

im using a level sequencer to edit an animation, i’ve baked it to a control rig and im using an additive layer to correct arm positions. (everything from the clavicles down, using FK controls)

i want to now mirror this additive layer or pose on another frame to complete the animation. i’m going to assume there is a method or tool that lets me simply flip it like in blender however, im struggling to find a way to do this. i cant simply copy and paste the values of the fk control bones on the left or right side and expect it to work on the other side.

i dont want to have to manually pose it after creating the initial pose because that’s inefficient, there has to be a quick way to simply “mirror” my character’s arm positions or pose onto a another keyframe to have them swing normally like any other run animations.

Some info: im coming from blender, i am not read enough to cleanly import the skeleton and animation to blender and then export it back to unreal without complications, staying within unreal is cleaner and simpler. googling only tells me about how to use a mirror data layer to mirror an entire animation sequence. i tried baking the single frame of my current pose and including it in the sequencer on a separate mesh to then see if i cant extract the location and rotations of the control bones from this now correctly posed character, but of course the data is absolute and therefore not usable.

any and all help is appreciated, i am at my wit’s end.

bump

I know this post was from a while back, but I’m working on a similar problem and I thought I would mention that, in the editor Animation mode, there is a poses tool that lets you save and paste poses to selected control rigs. With the poses tool you can also mirror paste the saved pose onto a control rig.

However, I have only had success mirroring poses using the pre-built control rigs for Manny included in the 3rd person template. I have not been able to accurately mirror poses on any control rig I build myself. A similar unresolved issue was mentioned here.

If anyone knows how to make a control rig respond correctly to mirror pose pasting with the pose tool I would be very grateful for the help!