She appears neither in Medlands nor in the Annals of Ulster, but Wikipedia lists sources, none of which I've got access to at the moment --
References[edit]
West or H-Iar Connaught Ruaidhrí Ó Flaithbheartaigh, 1684 (published 1846, ed. James Hardiman).
Origin of the Surname O'Flaherty, Anthony Matthews, Dublin, 1968, p. 40.
Irish Kings and High-Kings, Francis John Byrne (2001), Dublin: Four Courts Press, ISBN 978-1-85182-196-9
The Great Book of Irish Genealogies, Dubhaltach Mac Fhirbhish: Edited, with translation and indices by Nollaig Ó Muraíle Five volumes. Dublin, DeBurca, 2004-2005. ISBN 0 946130 36 1.
The Leabhar na nGenealach, which is what the Great Book Of Irish Genealogies is, was complied in the 17th C, true, but from sources mostly dating from around the 14th C, and some of those sources were compilations of much earlier texts.
The section on the descendants of Brian Boru is a fabrication, but I can’t speak to any ancestors he is given, and I haven’t the text available.