A word by any other name ...

[Aiwendil]

Bethberry wrote:

This would work against the idea that The Silm, TH, and LotR are simply set in an earlier age of our own world.

Not necessarily. If Tolkien's Legendarium is purportedly our own world, it is our own world some 6,000 years ago (by his estimate in Letter 211). This would put the fall of Barad-dur somewhere around 4000 B.C.E., which is just about at the furthest extreme of our knowledge of European language. Quenya, Sindarin, Westron, and so forth as presented in LotR would have been (very roughly) contemporary with proto-Indo-European. So one can in fact self-consistently pretend that these languages existed in our distant past but are, largely or entirely, unrelated etymologically to any modern language.