The phoenix each do have a spot for zetas, but yes, the hint "rises from the ashes" indicates Phoenix and "familiar foe returns" just means the Thrawn event is back.
I think they're too early for a rework, and I think they're kit is just as powerful as intended. They are amazing survivors for PvE, even at low gear, and I think that's what was intended. I wouldn't be surprised if they added zetas at some point, though.
I like your thoughts for Hera. Backup Plan on herself, yes, please. But just looking at their spots for zetas:
Hera - Play to Strengths (her special): Zeta could add a cleanse or slight heal for herself and the assisting hero.
Kanan - Total Defense (second special): Zeta could make this move also taunt, or perhaps this move could also heal in addition to the protection up.
Ezra - Flourish (dispel special): Zeta could make him gain +50% TM (If the enemy has buffs, that's 50% TM gain; If the enemy has no buffs, that would be 100% TM gain).
Chopper - All his moves already have omegas, so I don't know if he'll be getting a zeta.
Zeb - Staggering Sweep: Zeta could call an assist (making the Stagger debuff trigger instantly)
Sabine - Demolish (her AOE): Zeta could make the debuffs irresistible, perhaps?