Orson Scott Card has written some on King Mosiah, but I’ve got another point. He flees the land of their first inheritance. He arrives in the midst of a people who have fought many wars. Next thing you know, and the narrative doesn’t mention it at all, a Nephite faction leaves to go back, because they think they are strong enough to retake their homeland. That they come to grief surprises no one, but what should take your attention is that they think they can do it at all.
Think: Mosiah, Benjamin, Mosiah, three kings, in parallel, somewhat, to the King Noah and Alma, Alma the Younger story. Somewhere in there they gain enough additional strength and numbers that they think that instead of running away to avoid destruction, they are powerful enough to visit destruction instead.
Not to mention, whatever connection the second Mosiah has to the Church, and that Alma has as High Priest, when Alma has a religious/political question, Mosiah goes to his own priests to resolve it.
the church began to murmur, and complain to their leaders concerning the matter; and they did complain to Alma. And Alma laid the case before their king, Mosiah. And Mosiah consulted with his priests. (Mosiah 27:1)
Whatever is going on here, it isn’t the model I think most people have in their heads when they think of Alma as High Priest and Mosiah as a king who is a believer. He’s just a believer who has his own priests who aren’t part of the hierarchy, leadership or church that Alma is a part of, that Mosiah goes to when he has serious issues to decide.
When the writers say that the hundredth part is not contained in the book, they are not exaggerating at all.