The spine and neck components are hardcoded for a Y axis along the chain (this could be true about all components but have not checked).
It would be great to be able to choosing which axis is use as the “up” axis.
For example for quadrupeds instead of having the Y axis along the spine, it would be nicer for animators to have Z axis along the spine. This would mean that the axis are align with the world and animators are more familiar with the graph curves.