She will probably always remember it, but it is life. My husband accidently killed his dad's favorite bantam hen as a kid. He actually just stepped back and stepped on the chickens head. Total accident but it was his dad's reaction that he still remembers. You did well in doing the funeral and hopefully helping her realize that it was an accident, and the whole circle of life thing... Don't let her shy away from the other chickens though, she doesn't need to develop any fears...
I hope the sister hen gets over her loss too....soo sad for both those little girls!!!