Twain vs google translate

Google translate ran into a bit of a problem when Twain begins quoting the peculiar vernacular of the plans folks in 1830. How would google know that? Most of it was recorded by Harte and Twain themselves, so google is stuck in an uncertainty. It cannot translate all of twain until it had arleady trained on Twain.  But otherwise, google did real well because Roughing It was a straight forward diary of a young literate on a trip, grammar well defined, chosen words uniquely translate into the closed environment of the story.  I other words, google translate always has sufficient context to easily resolve ambiguity.