The axis may look different, but its probably not.
Dual quaternion is just better rotations, not necessarily better mesh skin precision.
What’s happening in your cases, aside from having no JCM, seems to be a precision driven problem…
Usually, it’s explained solved on topics that complain about morph target shadowing / display issues.
The reason behind the lack of precision is simple.
This is a game engine, not a 3d app.
You can change the code and build from source to increase that precision - but it isn’t needed for most if not all videogame, so it’s not the “default”.
Change the threshold value to your liking, compile, and import the mesh.
If the issue was the weight paint precision, it will look much better.
If it wasn’t, then it’s probably a missing JCM…