Board Thread:Suggestions forum/@comment-26949898-20170607140255/@comment-25101089-20170607223038

Recall that Dorwinion is a Sindarin name, and was once a vassal province of (Sindarin-speaking) Gondor, and its name is a "testimony to the spread of Sindarin" (from Tolkien Gateway, from History of the Hobbit, from Tolkien's own notes). It's not unreasonable to imagine Men or Elves would have spoken it, if only as a lingua franca.

One can speculate about what they might have spoken. But at the end of the day, for the mod's purposes, Tolkien has given us Sindarin and Quenya, we don't have any alternative languages to use, and I'm not about to consider making up languages when Sindarin is already suitable enough and has a large corpus of names.