1. Everyone makes typos and typos are extraordinarily hard to find. There's a whole profession devoted to finding them in the publication process and it's not for 'normal' people. It should be automated as much as possible and y'all could agree that no one will check stuff in that fails a typo check (similar to requiring that code that is checked in must compile without warnings)
2. Dyslexia, etc. doesn't matter. What matters to the team is how the team is affected. I wouldn't worry so much about things I can't fix so easily (his denial) and focus on the things you can.
3. You could have a private conversation with him after finding out the better practices that help people move away from denial. One tip I believe is that the person whose behavior we want to change must feel fully safe. Sorta like the difference between when a friend tells you teres spinich in your teeth vs the group's jerk.