I use some tricks in my addon to achieve similar functionality. Like, if you start a looting within 3 seconds after unlocking a lock, then it can be presumed that you just unlocked a treasure chest (rather than a locked door or something). It's not an accurate detection, but due to the limitations of the API perhaps there is no such thing as a truly accurate detection.
While I know the general implementation, I also haven't seen such an addon before. Maybe you can implement one yourself
