To tell the truth, I never heard of Idina Menzel either, however, the Dyslexia makes him see the letters differently, thus his mispronunciation. Yes, I find it hard to believe he did not check on the name if he did not come to the rehearsals.
A man I know, who sometimes has to do scripture reading at church services, always practices before hand, and his wife helps him with Biblical names and places that he may see differently than others do. So he practices, and really, if he had not told me his problem, would never know.