Does Cithria of Cloudfield's trigger still go on the chain when you play a unit if she's already buffed, giving the opponent a chance to play reaction spells?

Ruling: Yes, Cithria's ability triggers and goes on the chain every time you play a unit, even if she is already buffed, giving your opponent a chance to play reaction spells.

Nuances:

• If Cithria loses her buff somewhere in the chain of reactions, she will regain it when her ability finally resolves (assuming she's still in play)