Dear Eyes,
I imagine that therapists are no different from anyone else, where N is concerned. Reading a textbook or even having N's as patients isn't going to give the full picture. It's the difference between head knowledge and heart knowledge... anyone can read about a topic and get a level of intellectual understanding, but until you've lived with it, you don't know.
For instance, my divorce attorney has practiced law for many years and many of his clients have been women with abusive husbands. He understands manipulative jerks. But he doesn't "get" NPD. Throughout the 2 years it took me to get free of N-ex, my atty would propose this method, or that tactic for dealing with his NoNsense. At first, I'd say "that won't work.. it'll backfire...he'll use it against us"... and he'd shake his head at my "ignorance". By the time N had sued me for contempt of court on an order that he himself had failed to complete, this lawyer was asking me, "what should we do now??" Maybe now he gets it. I sure hope so.
When it comes to N, the person who's lived it is the expert.
Kelly, Your mom and the chaos she generates around her will not likely change, but you are full of possibilities and loaded with potential!

Hope