Aeon ACU has a sight range upgrade that gives significant omni coverage. That is a faction-specific intel-related advantage. And it's probably underused. Maybe give Aeon T2 radars some useful (but not OP) amount of omni range. I'm talking about just barely enough range to be worth making on the front line against Cybran stealth. With that, Aeon would be the "anti-stealth" faction.
Give Seraphim ACU a second upgrade to gun range & speed, where shots add a radar jamming effect where they land. As long as the unit/building being shot is alive, it will have visibility that basically counteracts the jamming completely. When the ACU kills things, the jamming would have some meaningful effect.
And for the regen aura upgrades: when the ACU is shooting, it should create a temporary jamming field around the ACU. It only turns on when the ACU is shooting because otherwise that might make it too obvious where the ACU is. Presumably if the ACU is popping off shots, it's location doesn't need to be kept a secret.