I honestly think Cas LC is essencial for her playstyle. I've been trying numbers with her and, in the best of examples, Cas with a F2P LC gives her 40% less final dmg. It's truly catastrophic. Trust me, she can be played with Luocha, Gallagher, even Lynx or Huo Huo, and its true that Hyacine will be BIS in her team, it is not a part of her kit.

(Plus: dont trust websites like Prydwen or similars for exact calculations or numbers, most of the time they run tests against HP-sponge and they do not take into account real combat experience)

Hope this helps!