I think you have an extraordinary level of insight into your sister's dysfunctions ... but sometimes having that insight means you keep running it around in your mind, developing and elaborating your understanding. You sound a bit like me (oldest sibling with messed-up younger sibs, academically high-achieving but pretty dorky, very good with words and ideas) - I know that I have spent far too much time parsing the "whys" and "hows" of a couple of dysfunctional attachments (brothers and alcoholic ex) when I might have been better off to just say "they're whacked, that's why they do that stuff".
I don't think this is an official Al-Anon slogan, but "not my circus - not my monkeys" is something I've been trying to put into practice with varying degrees of success for a long time (see also: "not my Happy Meal - not my fries", "not my rat - not my fleas" etc ...).
(I should note that my relationship with one of my brothers is now vastly better than it ever was when we were growing up. I think we both got enough distance from family-of-origin dynamics after a few decades to be able to appreciate each other).