When you teleport the character do you take the offset of the player to the center of the trigger volume into account? The player likely never enters the volume in the exact same place so when you teleport him to a mirrored location without that offset a change would be noticeable.
So basically just subtract the players location from the collision volumes location(or the mirror point of your teleport location) save this vector in a variable called Offset. Then when you make your teleport transform subtract the Offset from the location you are going to teleport them to. EDIT: Also if you’re teleporting to a mirrored location where you rotate the player π you would ADD the offset opposed to subtract it.
I’m sorry if this is something you already thought of, it just seems like it would be a common oversight in my opinion.
Cheers