Should I keep -Atk/+Spd Bridal Cordelia?

If she is your only one, yes.

I happen to have the same iv spread, and she's still pretty good. She's not going to be as powerful as a neutral attack, but the +speed lets her quad more often, which kinda makes up for her low attack. Also I still use her with her desperation quad set, two dancers with wings of mercy, and a bonus hero, and she can usually get me perfect tempest trial runs, so she's very useful for at least that.

Try to patch up that attack with the plus attack sacred seal. At least that will get you neutral