I dont know how managable that would be, because its possible, and quite common, for an entity to have multiple
actions attached to it at the same time. How could that be handled?

You say its in YOUR editor right?
So are YOU(or your code at least) assigning the actions to the entities?
If so, when you assign the action, cant you save the action name into a spare skill of that entity at the same time?
Say, at the start of the action itself?
eg
Code:
action player_act()
{
   wait(1);
   my.skill25 = str_create("player_act");
   ...


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