There have been a couple of novels written mostly or partially as in-universe books about alien cultures but from a human perspective, The Final Reflection (a work of historical fiction by a 23rd-century human author about events in UFP-Klingon relations from several decades earlier) and The Romulan Way (every other chapter of which is part of a "nonfiction" text on Romulan history written by a deep-cover anthropological observer). But the only book I can think of that's actually been written from the perspective of a member of an alien culture is A Stitch in Time, which is entirely told in the form of Garak's memoirs. I know the novel Kahless revolves around the discovery of a document purporting to be the true memoirs of Kahless, and alternate chapters in the book tell the story of Kahless' life, but I can't remember whether those chapters are actually written in the form of the memoir or are merely a depiction of its events.