Thank you for the response and tip on the (TRS?) Cable for remote control @VirtualGuitars
The main part of my confusion was that I thought I needed to make sure both L/R input signals were connected to the amp in order to get true stereo effects.
After reviewing the block diagram for the Roland JC-22 AMP, I was relieved that this isn't the case.
All I needed to do is add 1 more cable from 1/4 Out (Right) from the Helix -> the Return signal (Right) of the JC-22 for Stereo.
DeeJei's post in 4 Cable Method*?!? Helix & Roland JC series Stereo Amps was marked as the answer