Commenting in animation timeline or keyframes, commenting attachments or constraints, only visible in spine editor and not being exported, would be a big improvement for big teams or companies with more than one animator who uses other animators rig's. Sometimes something in the rig is so specific that it has to be explained by the animator, when just commenting like in programming could solve some questions. Maybe even taking notes for myself after coming back to a rig, or commenting changes over time or remembering some keyframe timestamp for tomorrows ideas.
