High-wings are more laterally stable, but not because of any pendulum effect - there is no such thing. It's because of the local up- or down-wash at the wing root due to the curviture of the airflow around the fuselage, while in a slip.
The air splits at the middle of the fuselage, and the upper half goes above it while the lower half goes below, and then curves around to rejoin. This means that for a high wing, the leading wing is in upwash, which increases AOA; while the trailing wing is in downwash, which decreases AOA. This causes a roll toward the trailing wing, which is stable.
Everything opposite of the above, for a low wing.
More detailed explanation, and with pictures:
https://www.av8n.com/how/htm/roll.ht...ther-slip-roll
(These upwash and downwash components are separate from the upwash ahead, and downwash behind the wing due to lift production that are more familiar to most.)
The false reasoning that leads to the pendulum fallacy is that one considers the plane to rotate around the wing root, with the mass concentrated at the CG wanting to hang down. But that's not so; the CG itself is where the plane rotates around, so the vertical positioning of the wing has no bearing on the act of gravity on the CG.
This is similar to the rocket pendulum fallacy that is based on rotation around the engines.