According to my own experience as a fluent English speaker who has a strong accent, modern voice-recognition systems have no problem with my accent, but I agree that they have flaws. They're not perfect, but I expect that they're more accurate than teachers because teachers have motives other than accuracy.
Several districts have sued TEA to block the release of the last two years of ratings, arguing that recent changes to the metrics made it harder to get a good rating and could make them more susceptible to state intervention.