Reading my second favorite Star Trek novel The Romulan Way for the upteenth time, and caught something new:
Since one of the generation ships the proto-Romulans leave Vulcan in was named Rea's Helm, the folktale the name comes from must have been already known on Vulcan, rather than being unique to the Romulans.
From the way Ael told the story in My Enemy, My Ally, I had assumed it was a Romulan myth; Spock certainly doesn't mention knowing it already. But if they were already using the name before they left Vulcan, the story behind it must have been older than their departure.
(I don't mean to suggest this is a continuity error, certainly Spock wouldn't know every single myth and folktale of his homeworld, any more that any of us do. This is about my preconceptions and how they were wrong.)
