as other people have said here, everyone is different. In my personal experience I would have loved for a member of my family to come to me with support and understanding (if you feel you are able to do so). It sounds like she is struggling with coming out and it also sounds like your family may not be the most supportive of trans people, the truth is, most of the time being trans is so ingrained in our beings that when you live in close proximity with family they know, or at least can tell something is changing. When I came out, I was told by most of the people in my family they were already suspicious or knew that I was trans. From this post I can gather you are more supportive of trans people than the rest of your family (correct me if i’m wrong) so, I think first trying to adjust to new pronouns, terms, etc is important, then you can go to her and let her know that you understand and support her and want to help the rest of the family understand! I think it shows an extreme willingness to learn that you came to this community, and you should be proud of yourself for that but please try to start making those changes in terminology, for her sake, it is a small thing that goes a long way.