Use 5C instead of 2C. 623[A] only grabs when they're too high and both of them have really high falling hitboxes.
BTW Wara and Kouma's falling hitboxes after a groundbounce are gay. It's impossible to 2C them after j.[C] no matter what. You can do 5C 623{B} 2C 623C 2[C] 623{B} xx 236[A] for that 236[A] crossup/fake crossup if you want. Or maybe you can just do 5C 623[A], which I haven't tried yet. You can never hit 2C or 3C though, since they actually touch the ground and become un-OTGable before their hitbox gets low enough to 2C them.