And from what I know Appo was promoted to Commander of the 501st shortly after Umbara

Do you think this was part of Rex's consequence for what happened. Because honestly the Kaminoans don't care. The clones are supposed to follow orders and keep the others in check. They're all expected to obey. His consequence wasn't too severe because Krell was a traitor and he had probbaly been backed by several clones, Anakin and Obi- Wan