My two cents, as a practical person and a thorough enjoyer of Stormblood AST. for me AST's main problem right now is the weaving nightmare it can become at times where you need to set up heals and throw out cards.

Make Draw and Play GCDs with reduced cast time (like dancer steps or ninja mudras). Same MP regen on Draw. Still two charges of Draw.
Return of Royal Road and just make it double the next card effect or duration for melee cards, and AoE cards for ranged cards. (perhaps a one minute CD on Royal Road)
Get rid of the Seals, but keep Astrodyne as a reflective self buff (perhaps MP regen if Draw is on CD, dmg and healing up if a card buff is up on the party)
Make Synastry work on Cards too.
I'd steal the idea of Eukrasia from sage to have an "Aspected" buff that turns Benefic / Helios into their aspected versions (and Malefic into Combust I guess) to help with button bloat. Otherwise, just merge Benefic I and II with Aspected Benefic, with both a direct heal and the regen.
Add back the buff duration up on Celestial Opposition. Bake in the single target version of this in Celestial Intersection I guess.

I'd be happy with this. More time magic, more card play, slightly less oGCD weaving and we keep the great healing CD setup.