Instead of changing "governments to singular, why not change "these liberties"? The sentence would end up looking something like this: "Governments must be organized to defend liberty from themselves, their counterparts, and from the criminal acts of individuals."
I still think "success" is too vague. Success at what? Well, it's left undefined at the moment, so it can be anything towards which a society sets its mind. I think, however, that the ProP has a vision, and that this is as good a place as any to express it. Like so: "The progress of society towards justice and the progress of individuals towards their potential are fundamentally linked." We want to move forward towards a just society of the most full and complete people (and we're asserting that the movement of history is in that direction). Besides, we're the progressive party, and the word should appear somewhere in our platform that's not the heading or the statutes.