Setting up Generic 6DoF Joint spring parameters (Stiffness, Damping) for pose driving

Godot Version

4.8.dev2.mono

Question

Thanks to a recent contribution we can now set up proper spring targets via quaternions, and that's great. However, there is no documentation or discussion I can find about how to actually set up the joint parameters properly to drive a body to a desired orientation. This is further complicated by uncertainties within the API.
Jolt has three spring modes. There is no spring mode setting exposed in Godot. How do I know which mode (“Stiffness and Damping”, “Mass Normalized Stiffness and Damping”, “Frequency and Damping”) is actually used? (Other than deducing it from playing math detective. Which I will do, but it would be nice to just have this information plainly available.)
I was also hoping to maybe find someone who has set up joints before and can share their experience, like what values lead to realistic behaviour for certain configurations (like shoulder joints in a ragdoll for example).
If anyone can provide some more info on this I’d really appreciate it!