It is a bit disingenuous to jump from

> polymaths and prolific artists and writers and educators

to composers. Even the male composers of whom we know the names are few and sparsely attributed. Just look at the Notre Dame school and how little we know except two names with no attached biography and some beautiful music. And even only that by 'lucky accident' since a single, anonymous student wrote them down.

You'll definitely find abbesses like Herrad von Landsberg who did write and educate in her generation.