I'm pretty sure it's a Single Acting. I had a MIJ WL5 a few years ago and it was Single Acting. I do not know for sure it all MIJ WL5s were, but, mine definitely was.
While graphite rods can technically be considered truss rods they would generally be called stiffening rods. If you refer to the picture below the truss rod is the blue piece in the middle of the neck. The stiffening rods, possibly graphite or CF, are on either side.
No idea what kind of truss rod is in the Will Lee. Single acting, single rod wouldn’t surprise me.