I think this is an interesting (& also a valid) question. But, unfortunately, I don't know as I have any particularly useful answers. I think, based on my own experience, the only way to tell is to pay attention to how you're doing on the medication & try to compare that with how you were doing prior to taking it.

A while back, I started taking a low dose of clonazepam after having been off all medications for several years. There were several reasons I did this. But one was that I felt myself becoming increasingly angry & reactive. Am I better now that I'm on the medication? Yes, I can see that I am. It's not perfect. I still have to work at it. But it's better. That's pretty subjective. But it's the only way I know of to tell. I suppose you could also ask people you're around day-in & day-out if they've noticed a difference. But ultimately I think whether or not you're getting better is something you have to determine for yourself.