… The character chart says 1 for each of the four character types, but still has 1 for each of the two wizard types. 5 character cards for 4 players.

A: Remember that the alignment cards are not dealt out until after the character cards are, so:

Deal out the character cards, one to each player. There are four of them, one per player. No problem.

Only one person is the Wizard. Now scramble up alignment cards one Good & one Evil and give the Wizard one randomly, face down, and put the unused alignment away with nobody else looking at it. The Wizard now looks at their alignment card. They are either Good, or Evil, and only they know which.

Voila! You have four characters: a Guard, a Traitor, a Keyholder, and a Wizard (who may be either Good or Evil).