When members join the Café they are asked to supply a, "username you wish to be known by at the Café." Should members expect their real names to be kept private by the Magic Café staff?

Depends on if the member wants to reamin anonymous. Many members join with a username and then use their real name in posts or someone who knows them uses the name. Unless the member specifically asks us to delete any reference to a real name, we don't second guess the situation.