Holy shit sisters, fucking finally. Last time I couldn't even break this boss once after several attempts using one of the teams on the guide, eventually got tired and I ultimately got filtered. Now that my Homu is A3 I knew I had everything to beat this thing.
As other sisters had already said, you really gotta mind when you use Reira' special and you have to dispel the witch whenever it has a damage dealt up buff, that's it. Most of the familiars can be broken before they can even act if you have the right team comp with good support.
Also funny how the moment I switched out my A2 Felicia for A1 Tsuruno I started dealing damage way more consistently. Buffer + debuffer is the way to go it seems.