Oh hey! We both did typing games! :D
I really like the mechanic of yours - switching between the different characters really upped the difficulty! But in a good challenge kind of way.
So a couple times I would be typing a word as Adam, but because the word contained the letters e v e in it, it switched to Eve and I wouldn't realize what was happening and have to scramble back to not lose a life. It felt a bit frustrating when that would happen. Maybe if the switch between characters is telegraphed more (a sound effect on switch, or something big visually?) but other than that I don't have anything to add, it's a really neat take on the limitation! Great job!