When someone adds an emoji reaction to my comment, I would like to be notified about it. That way, I don't have to remember to go check my old comments to see if anyone responded with an emoji. This would let me rely on emoji reactions as part of our workflow.
However, I would like to make sure that I am not 'spammed' with with a lot of emails if many people are adding emojis. Perhaps just add the emoji reactions to the notifications page inside of Aha! and show the orange 'notification' dot next to my profile when a new one is added to my comment.