I never thought it made sense for Anakin to be mentioning Leia while he’s dying.
I’ve always thought it was ambiguous in ROTJ whether Vader even knew that Leia was his daughter.
He figured out that Luke had a sister, but he just refers to her as “twin sister” / “your sister”. I feel like he would have referred to her by name if he had been able to figure out the actual identity of Luke’s sister.