Hmm about lorelei, do I think she could beat Medea in a fight? No, no I do not, not in the slightest she is in the range that Medea would take the most seriously and though she's strong I do believe that Medea is a lot stronger.
However do I believe that her stats are correct? Well... Maybe, And that comes from what I know about another clock tower magus, Kayneth. Apparently he's a prodigy which apparently includes having an insane magical capacity something like 2000 when compared to Waver's 1. So that gives me the belief that perhaps she does have A rank though rather then saying A rank as a whole perhaps say something like A rank modern magic and have her AoG knowledge be a separate rank altogether.