There is a menu option in the X100S that tells the camera that the TCL-X100 is attached. This is supposed to tell the camera to correct for the lens's distortion. On my X100S, shooting Menu 3/Conversion Lens can be set to Off, Wide, and Tele. By analogy with what happens without a convertor, this should cause the camera to embed correction information in the raw file that LR will use to correct the image distortion.
You need the latest camera firmware, and you need to invoke that menu option. If you're doing those things and still getting distortion, then I don't know what to tell you.
Hal