That's right. They are a little hard to clarify though. Most of the sounds are just OUAGH and URGH in all different kinds of pitches. But I've definitely made plays based off of what I hear before.Each model has unique sounds when damaged on 100/75/50/25 health respectively. There's your damage indicators.
To be honest there's nothing stopping you from editing the different damage sound files yourself.So what you are saying is that we should make a client side modification that helps us distinguish these?