I got around to verifying it, Final Ultima is correct. You can do 5C relaunch from anti air 6A > 5D(1). If it hit's around head level, you can just do the 6A > 5D(1), but if it hits them lower, just add 5C in between to adjust the height.
(done on Ragna doing jC)
anti air 6A, 5D(1), GH > max delay 214D > 5C sjC, jD (JC), jC, jD, ID(D) etc = 2970dmg
with 5C in between the 6A and 5D, it does 3088dmg.
But yeah, I couldn't even get it to not be counter hit using it as anti air in this situation. So this is really only for if you don't feel like hit confirming, or are just hitting them for not air barrier-ing.
cool, thanks.