Depends on Crit. I don't think any of them are double damage. For example, Asherah is low chance for 20% extra damage. But remind you, at least at the moment, there's nothing in the same modifier. So 20% more damage actually IS 20% more damage. For comparison, P2W Eidolons are ~25%ish more.

SSR Cybele is 35% damage I believe, but I don't know the procrate of that. I'd imagine it's low.

How does Crit stack? Uuuuh... I don't know. I have no idea. Can you proc multiple crits? Wait, no, the buff probably overwrites... can you have a Crit passive? Well, you can Crit from your weapon Grid at least... uh, yeah. I dunno.