This is great, I also had struggled reading Moral Mazes and I appreciate the selected quotes.
For a more readable, modern treatment of the subject I strongly recommend Power: Why Some People Have It—And Others Don’t. The author draws heavily from Moral Mazes as well as other case studies.
Off the cuff:
Temperance movement in the United States
Much of the radical left movement from the 60s to the 70s (ex. Students for a Democratic Society → Weatherman)
Another useful line of inquiry might be factoring out what success for a social movement looks like, find social movements that “succeeded”, and see what happened to the social movements they were competing against.
+1 for noting mistake and for noting the importance of being bold, and asking questions and sharing models even when you’re uncertain.
Your use of the Epistemic status tag—which I think /u/gwern pioneered? - seems good for balancing the value of sharing models while preventing polluting the “idea space” with potentially misleading/untrue things.