How does [Orientation Warping] node with "graph mode" calculate forward facing direction?

Dev Situation:
I am developing a VR project (PICO4).
The pawn is a child of ACharacter, but the movement is not based on the CapsuleComponent 's movement or rotation, thus i didnot use the default movement component of ACharacter for any movement logic.
Instead, i added a custome SkeletalMeshComponent and use its relative location and rotation (which is controlled by the location and rotaion of the VRheadmount) for movement.

Issue:
During development i noticed the orientation warping have issue determining the root rotation.
More specificaly, the root rotation doesn’t seems to be base upon the relative rotation of the SkeletalMeshComponent.
When the vr character’s movement direction is near parallel to the forward vector of CapsuleComponent, the leg orientation align with movement; however when the vr character’s movement direction is near ±90 degree to the forward vector of CapsuleComponent, leg anim orientate as if its walking ±50 degree.
I double checked the input orientation angle and the animation sequence for [Orientation Warping], both are correct (orientation angle within ±6 degree, and animation sequence is forward).
So i suspect the root cause for this is [Orientation Warping]'s graph auto calculate the forward facing direction based on the CapsuleComponent instead of SkeletalMeshComponent 's forward vector.
I cannot find the source code for [Orientation Warping], so i wanna know if my guess is correct, and if so, how i could fix it.