Running on around 25 attempts, killed second round of mini bosses 6 times, one attempt got under 10% - at which the lovely tail + swoop combo kicked in...
Have tried all from random pugs, to the most organised with sub groups, proper builds, roll distribution, all buffs (food, event buff, jadebot buffs, etc.) and every time the rng - especially at the last 20%, at which it feels like swoops becomes extra prevalent - always results in fails. If it's not constant swoops or tails (even after the supposed change to the amount of bite attacks), it's useless cc phases that only happens when tail is up, when she swoops or right before she phases.
At this point I just don't know how I'll ever be able to get this event done even once other then pure dumb chance of luck.
I got optimal gear, optimal buffs, optimal squad, all mechanics done with only seconds of mistakes, and it's still not enough, unless rngsus decides not to screw you over.
So to answer OPs question, you might be blessed by rngsus and get it within a few tries, or you might never be lucky enough to even consistently get to the last phase.
This is not a designed meta, it's a 2 hour gamble.