If you have E2S1 Phainon, Cerydra is not that good, and a downgrade from Bronya.

E0S0 Phainon is like having a big bag of fries (meteors) and no sauce (buffs). Cerydra is like getting a small bag of fries (extra meteor) and a little bit of sauce.

E2S1 Phainon is like having two big bags of fries (extra meteor). You could get yourself a small bag of fries and a little bit of sauce on the side (Cerydra), but you should instead get yourself a big bag of sauce for all of your fries (Bronya).