Hmm, I always knew it had to do with that Rachel specific. Just had no idea what to do with it though. I was able to Milk more damage and heat from this
FC 2C 6D ,delay j.D, dash 5C 2D 5B 5C 5D(1) 214D walk forward 5C 2C 5D(1) ,22C whiff, 22C dash 5A 5C 6C (DC) 6D (JC) j.C j.214C walk forward 2C 5D 623D(1)~Wallbound 5D 22C
Damage:6423 Heat Gain:73
Sometimes the final DID will hit twice, and while it's possible to walk 5D it, the 22C will miss. Probably bacause I didn't try hard enough or because she techs way too early before the required distance of walk 5D.
It would deal 6465 damage otherwise.