If I wasn't even know I was a 4w5, you should probably not to take my opinion about her type so seriously. Well, I cannot definitely rule out her being a Four, (I probably did not understand what could be classified as a Four anyway) but regardless what type she is, she is most probably an unhealthy type.
She had been a nightmare in my life, we never got along well. To me, she was some sort of horrible creature. She tried to compete with me all her life, constantly crossing my boundaries and always said horrible things to upset me.
If I liked a certain TV star, she would say she liked the competitor of that TV star and put down the TV star I liked. When I was getting frustrated due to a cold, she would say I must be angry because I looked ugly due to the cold. When I was holding a baby and did not want to pass it to her yet, she said, "One day you will drop you own baby onto the ground". That happened when we were both still school-aged kids.
She was super-subjective. I was never able to reason with her on anything. She would bend everything to suit her argument. If she didn't like anything, she would just constantly argue with me or just got angry and went away.
I have only seen her cried once after she grew up. That was when she was beaten by my mother due to her rebellion. She studied literature at Uni and wrote poems herself. She had a big collection of books, but it seemed to me that it was more of a collection rather than her really reading them - as I rarely saw her read any book. She liked contemporary piano music. She was always tired and slept a lot during the day. She had been hospitalised once due to major depression.
She was probably not very self-referential. Whenever she accused me of something, she always had to emphasis that brother or sister or father also thought the same.
I was introduced to Enneagram by her, she was very keen to get me to do the RHETI test and asked me for the result. I guess I now kind of know why. She thought she was the "best type" 4 and wanted to prove that I was the "worst type" 3. So she would win. She got angry when she found out my test results. She kept on convincing me how I must be a Three. Fours must like cats, Fours must be unpleasant in character, etc... Since I was not convinced, she got mad at me and even made sarcastic remarks such as "If you are a Four, maybe I am not a Four then", "If you like to be a Four, be a Four then", etc.
One thing I agree though, it is impossible for me to be the same animal as her.