Glad to see this update coming soon.
Root motions on flips and the like is complicated, but very important for their usefulness in a game. My best advice is for the root to always be a set distance bellow the hips in world space, and to have the same yaw as the hips, but no roll or pitch. So, in a flip, the hips would do a full spin in the pitch axis, but the root would not rotate on that axis. If the hips are 100 units above the root, and rise 50, the root should also rise 50, maintaining that distance. I hope that makes sense and helps.