I think it would be beneficial to have the ability to change/add to the state list property type using expressions. both in an action and through a text box function on the fly.
example: say you had a task that checked how a player reacted to a punch. it would be nice if we could change it with an action expression like, character postion is standing if mood variable is enraged, sitting in chair if mood variable is unfazed.
as it stands right now you have to create two different system task to be called for each possibility, this would greatly reduce the number of task thus make it easier to edit projects.