Another problem with it (though maybe in a bit too much logical extrapolation for a Civ6 game) is that, if the Navajo were not subjugated by Spanish, then Mexican, then American colonialism, and made into an obscure ethnicity with next to no international representation on their own, but became a more modern sovereign nation in their own right, and had trade, diplomacy, alliances and wars, tourists, national parks, cultural influence, etc. as their own nation, the Navajo language would not be obscure enough, in that case, where Codetalkers would at all make sense. But, as I said, Firaxis, and many of their fans out me,
@Zaarin,
@AmazonQueen, and a few others here, are rarely pedantic and nitpicking enough to point out any details on that level about the game.