The naming of the different variants is confusing, but since this data is from el municipio de Cuetzalan (see the “Deposit-Nahuatl-…docx” file), it should definitely be azz. You can read about details of the different nahuatl spoken in the Sierra de Puebla here:  (PDF) A View from the Sierra: The Highland Puebla Area in Nahua Dialectology | Sasaki Mitsuya - Academia.edu
There is some audio included from the municipality of Tepetzintla, which is called “Nahuatl de la sierra oeste de Puebla” or ‘Nahuatl de Zacatlan-Ahuacatlan-Tepetzintla’ (code: nhi), but there aren’t any transcriptions for it.
I am still in the process of evaluating the model on my data, but I will let you know! I’m also working on a DeepSpeech ASR model with this same openslr data to compare.
Thanks for working on this, it is very helpful!!