I've included many of the suggestions in a recent commit. I settled for "New World Order" for fascist America; when I made that change I realized that my current name for it was "Empire of Columbia" which is pretty cool, too, so I used it for monarchist America.
Also, I also included leader changes into the same Python module, mainly because Rhye's mechanic was needlessly complicated in my opinion (leaders had a certain chance to appear after a certain year which doubled once you reached a certain era). In my version, the most leaders are associated with an era and appear once you reach it. Because the change isn't checked for every turn, this is not too deterministic. Civs with more than one leader for a certain era have more involved conditions there. Certain leaders are also associated with civics (Hitler appears only with fascism for example, Stalin when you're not in a monarchy etc.). This system could be easily expanded to include further leaderheads to show up under special conditions, so if you have any ideas (and the leader exists in the database), I'll see what I can do. Leaders shouldn't change to often, though.
Also, I also included leader changes into the same Python module, mainly because Rhye's mechanic was needlessly complicated in my opinion (leaders had a certain chance to appear after a certain year which doubled once you reached a certain era). In my version, the most leaders are associated with an era and appear once you reach it. Because the change isn't checked for every turn, this is not too deterministic. Civs with more than one leader for a certain era have more involved conditions there. Certain leaders are also associated with civics (Hitler appears only with fascism for example, Stalin when you're not in a monarchy etc.). This system could be easily expanded to include further leaderheads to show up under special conditions, so if you have any ideas (and the leader exists in the database), I'll see what I can do. Leaders shouldn't change to often, though.