I am not sure how this impacts BOM Historicity. Proto Uto Aztecan languages have been around the US southwest and northwest Mexico for thousands of years in an oral form. Are you suggesting that BOM people's interacted with Uto Aztecans of the south as did the Spanish Franciscans when they migrated here, using a Spanish model to create a UT Nahuatl orthography? If so. why did not that orthogrsphy exist into Hispanic times. It seems the Franciscan linguists would have piggy-backed on it? Or are you suggesting those who built Teotichuan list their written language due to invaders prior to the Spanish? I am trying to understand the connection and why it didn't survive into the 16th century? Thanks