to remove them the hollow bolt faces inward , so yes to loosen it you turn the 6mm allen CW.
the bolt through the lever itself is yes a 5mm one, the Nut is custom made by sun tour for themselves
thinner thickness , bigger hex , then there is a screw slot locknut on the outside you tighten against the nut, beneath it.
the 2 of them work together to set and maintain the retro friction.
I have a screwdriver with a notch in the center to get the domed nut tight.
someone posted a exploded diagram of them earlier this Year..