The explanation for which a CG lower than the pressure center should provide roll stability has never convinced me.
Suppose an external force makes you depart from level flight into a 30° roll. You're now in a turn but the forces will still be parallel to the vertical axis, so there is no momentum against the roll.
However, in the extreme case of a parachute/paraglider where the CG is much lower than the center of pressure there is a strong stability.
How is it, then?