If you’re making long charges there’s little chance the unit will be able to benefit from any auras as they are all within 9” or 12”.
It would need the Hero’s giving the auras to also make very long charges and that isn’t likely .
At the end of the day there’s a one in 6 chance of getting Wave of Terror with a single unit, it’s easy to work out how powerful on average that is.
Yes it’s powerful if you roll it on a huge 30 man unit of Grimghasts or multiple units. It’s also very weak if rolled on a Guardian of Souls or isn’t rolled at all. That’s where luck and statistics comes in.
Compared to SCE and Idoneth who have guaranteed charges with very hard hitting units it’s not that scary unless you get very lucky.
I’ve not heard any majorly competitive players suggesting it’s too powerful which speak volumes, in fact most people I’ve heard dismiss it as gimmicky because it’s not in the slightest dependable