Sorry this is a late response!
But as long as she's passing and getting the required marks, she would be accepted to Dilys. There are no canon mentions of how one furthers their training/education after Hogwarts. So everything we do that involves the healing school is all from what we believe would be the case given the information we do know. Applicants are interviewed by the school's Master and are then notified by owl if they have been accepted. There is no essay required or anything else other than the interview.
Hopefully that answers your question
