Of course, there are varying levels of "Authenticity" involved in approaching these different topics that wander farther and farther from a truly historical perspective, so to aid you in your search, we are labeling the pages in our wiki as one of five basic "levels" of authenticity, from 100% historically accurate, researched, and documented, all the way to 100% fantastical, so that you can find exactly what you're looking for.
Authenticity in reenactment is an interesting question, and can mean very different things depending on reenactment groups, and era/genre being reenacted. Also, By it's nature, Middle Earth Reenactment is an inexact thing. The Lord of the Rings never happened. How can you "authentically" reenact it?
Authenticity can probably be best approached by pulling apart and examining it's component parts. For our purposes items will be rated separately on historical faithfulness, and their fidelity to Tolkien's original works.
Tolkien: Is something a faithful representation of what Tolkien actually described?