A plugin might simplify what you have to deal with within the editor, but again doesn't seem like it needs a plugin.
You can just attach a "change mood" common event to every item and skill. In the common event use variable controls to set the value of the mood.
Linearly, with a single variable, I think you could just dedicate a range to certain emotions.
Judging by that picture, there are 12 emotions.
So values 11, 10, and 9 are happy.
8, 7, 6 are sad
5, 4, 3 are neutral
2, 1, 0 are angry
(or some variation of that)
So the common event would either add or subtract the value. Then the troop event will check what that variable is at and assign the correct "mood" (state) to the actor.
There are flaws with this that would need to be thought through - I'm not dedicating the necessary brain power to something I'm not implementing in my game - but so far, it doesn't seem like a plugin is necessary unless you want to simplify your work in the editor or you just don't know how to utilize the built in logic of conditionals and variables.