I have noticed for a while now that the animations for these two spells get messed up when you critical with them, the screen pans off to the enemy at the wrong time and therefore it gets really hard to see damage dealt.
I've noticed that to! I was thinking that maybe the screen is moving to slow to catch the attack that occurs within a few seconds. Sometimes, which happens very rarely, when I would critical with mana burn, the screen would come around just fast enough for me to see the attack number fading. I hope they fix this Although, I haven't noticed it with super nova, perhaps it could be something that doesn't happen to some people and not everyone?