O.K, about the Katara revenge thing, I know people can interpret the same work in different ways, but I don't think scaring the shit out of the old men really classifies as revenge. Normally when you get "revenge" on someone, what you inflict on them can be comparable to what they inflicted on you, basically "getting even". Sure Katara scared the crap out of the guy, but that's hardly comparable to what he did to Katara and her family, most people would say that Katara did not "get even" with the man. Hell, the guy even offers to let Katara kill his own mother as a way to get even (at least by his standards), and it's that offer that makes Katara realized how empty and sad men like him are and end up being the defining moment what Katara decided that revenge isn't worth it. I mean, I guess I could understand how a someone younger could look at that scene and think "Yep, Katara got her revenge" because Katara probably did get some satisfaction out of scaring the guy, but I doubt that could compare to him killing her mother and forcing her and her family to grow up without her. It was a bit of cold satisfaction, sure, but I personally would hardly call it vengeance.
As for Lily's channel issues, I agree that the problem isn't Mikalia, it's that she isn't using Mikalia particularly well. First off, Lily has a "golden goose", she's had one for several years now; her "X is garbage and here's why" videos. She's only made two of them and yet both have broken over a million views each, they pull people in. Even if a lot of people outside her audience just come by to marvel at how batshit insane and petty one person can be over a cartoon, revenue is revenue. Obviously these take a lot of her time from other projects, but now that Mikalia's working with her, she can off-load some of that work onto her, hell, if she tried she could probably get more of her "inner circle" to help her for cheap if she fished around a bit. If you want proof, just take a close look at all the biggest Youtubers on the site, almost all of them have teams helping them produce content at a regular schedule.
But whatever happens, the only way Lily is going to fix her channel is if she makes some changes to the content she produces. Though she might not want to admitted it, the age of the angry reviewer is on its way out. Sure, sometimes a channel can break the mold, but most people are getting sick of exaggeratedly hostile personalities who make bad faith arguments and nit-pick every little detail. If she doesn't make some changes, her channels future isn't going to be very bright.