"he did win another typing competition using the CharaChorder to hit 267 WPM with 76% accuracy." 76% accuracy doesn't sound so great to me, no matter how fast I can type on it.
With such programs, the WPM score measures how many total times per minute you "finished" a correct word, including any time spent correcting the word; with the accuracy score measuring how much extra work was done, on average, doing those corrections.