The Tahitian legends are documented in the book "Ancient Tahiti" by Teuira Henry. "Ancient Tahitian Society" by Douglas Oliver also mentions it. "Vikings of the Sunrise" by Te Rangi Hīroa (Sir Peter Buck) mentions the Mangarevan legends. There's also other accounts around. I first saw it written on a sign at the archaeological remains of an old Marae in Mo'orea.

The histories of Pitcairn are kept alive through cultural studies taught by the islanders to the school kids.

Yes double, where did you learn this? It's fascinating