Mr. Sunday Movies pointed out something interesting about the shot with Leia in his breakdown.
https://youtu.be/dcDZ67rHxgI?t=87
They may have used CGI to digitally layer Carrie Fisher’s face onto another actress. I don’t know if that is true, but so far what I am seeing of Leia definitely is doing a very good job of not taking me out of Episode IX and making me feel as if I’m watching footage shot for one of the other films.