The upper has greater tension than the intermediate. The CS36T manual has a detail section on tuning the rig have you looked at it?
The funtion of these shrouds is to keep the mast from falling off to leeward, they operate unknowing of the backstay. Tune them so when beating in 15-20 knots, the masttrack is straightand the leeward rigging shows a little slack but doesn't flop around.
Certified...in several regards...