Regarding how it currently is, can reactions be at least toggled on and off, or are they passives that fire off whenever the cooldown or whatever is up and something triggers them? At the absolute least, they need to be toggled (e.g on any given turn, be able to click a reaction icon to make sure that reaction is active or not). Now, if reactions can be toggled (i.e activated when you perceive an incoming use for them), you would think that the AI would be given the option to do so as well, which would be performed by establishing certain conditions, such as when AI knows to drink a potion (basic AI stuff). If conditions then exist, wouldn't we be able to use them too?
(Yeah, I know, lots of "ifs")