If Mason is picked via Random, and no Mason Leader is picked via Random, you can end up with Masons with no purpose or ability. I propose that in the event Random selects one or more Masons but no Mason Leader, one of the Masons becomes the Mason Leader if the "Replaces Mason Leader" option is checked.
Otherwise, include a second checkbox under Mason for "Always have Mason Leader."
I played a few builds go where I was on a team of 2 masons but no Mason Leader. We were effectively citizens who knew eachother's identities. If this has already been changed, it escaped my notice.