always thinking about tolkien's absolute galaxy brain move of making westron a whole language (well it may not have been as detailed as e.g. quenya & sindarin? but even so), but then completely replacing it with english in the books
And the sheer detail that went into Tokien's translations of names.
For example,
“Banazîr” is Westron for “half-wise, or simple.” In Proto Germanic, the prefix “Sam” means half, and wise is obviously a word we still use.