The buds look to be ok to me. If they have been damaged, they would have become blackened. Also, eventhough the temps for your area maybe 24F, it looks like your tree peony is grown in a sheltered spot(a warmer microclimate), protected from winds and cold by your fence. As a result, your tree peony buds are safe from freezing. Had that TP grown in an open field with buds like that exposed to 24F, I think they would have been frozen and turned black or brown.
