In Socionics, she's probably an EII--her Fi driveness is obvious from the fact that she is so strongly driven by morals, and her form of imagination is clearly N over S. In the MBTI, she comes off as one of the two INF types. She, or rather she as Robert Galbraith, says INFJ, and I'm inclined to think that she knows what an INFJ is, considering that she also correctly types Dumbledore as an INFJ. I also detect J from the fact that she is big on working out the plots of her books in advance. I think an INFP would be very unlikely to do that, being a Perceiving type in how they interact with the world around them. As for function strengths, she is clearly strong in both kinds of feeling as well as both kinds of intuition (the Harry Potter books are overall more Ne than Ni; on the other hand, The Silkworm, written under her pseudonym, could only come from someone with strong Ni.) I think where people are sensing Fi is from the fact that she's a type One on the Enneagram, which often looks Fi-ish.
My final verdict is INF?, with INFJ being somewhat more likely than INFP.