I have three White Rifles, and all of them come with a left sided cocking lever on the hammer striker. You'd think that would be a problem, but actually once you start shooting it, it never even crosses your mind. Like you said, no shell jumps out, and its not rapid fire.

Now a left handed shooter can have problems getting used to a flintlock that is for a right handed shooter. Only because the spark and flash is so close to the dominant eye. But even they master that with time.