[Lombra]

Yes, it seems the text is only updated OnLoad (when the buttons are created, you won't be able to hook that) and when bindings change.

You could either call the hook for all buttons once in your addon, or hook some other function in addition, such as ActionButton_Update, which seems to fire on PLAYER_ENTERING_WORLD. That's also called on a lot of other occasions probably, so the former is probably the better solution.