I'd say she's easy enough that using HP eidolons to survive is fine. The fight on auto-battle is more or less surviving the raging overdrive and she's pretty much dead after. If anything, gimping your damage a little could possibly be a good thing and giving you an extra turn on the trash. If you're using something like Trial by Jury and your damage is low enough, you'll have enough turns to charge the cooldown back up by the time she uses her rage overdrive.
Though for my dark team, I'm pretty confident I can defeat her every auto battle now after some testing. Decided to put Amaterasu on my sub. Spinx''s raging overdrive always takes out 1 or 2 of my himes, in which Amaterasu subs in. With Amaterasu spawning after the raging overdrive, she can now user her -20% atk/def debuff and her regen prevents my himes from dying from the debuff, which I thought was patched but still works after a few tests.