We covered this here and I asked if we can focus the topic so as to make it easier for others to search and learn from.
I’m not seeing this here, so to answer one of your questions:
See the Advanced Pose tab of the Marker to control stiffness for Twist (X) and Swing (YZ) separately.
Another thing you can try depending on what your looking for is leaving stiffness equal across all axes, and adding a narrow limit with less stiffness so as to make the limit prevent rotation softly in the axis you need.
PS: I’ll edit the title too to make it searchable.