IIUC, it's trained on LibriVox audio mainly, along with a few other sources. I'm not sure how it is handling spelling as the spelling will depend on the source

IIUC, it's trained on LibriVox audio mainly, along with a few other sources. I'm not sure how it is handling spelling as the spelling will depend on the source content being read, unless the source text has been processed/edited to align with the dialect.