I'm not denying that Civil War could easily be about peace of mind.
What I was trying to relate is the fact that the language "Peace of mind comes to those who..." does NOT reference a goal (nor a Story Goal) in the Narrative Argument format. Whether the goal is or is not "peace of mind" has no effect on the "Peace of mind comes to those who..." verbiage. That verbiage results from stories that have Linear/Changed/Failure/Good story points.
It is only those four points (Problem-Solving Style, Resolve, Outcome, Judgement) with those values (Linear, Changed, Failure, Good) that can result in a Narrative Argument with that verbiage. Thus, using the verbiage "Peace of mind comes to those who..." as an argument for why "peace of mind" is the goal or Story Goal is comparing, at best, oranges to tangerines. Related, but not enough for conviction.
Now, to talk about the actual Story Goal, I'm wondering if what I consider as "peace of mind" is different from what you're considering as "peace of mind". Maybe an umbrella term for guilt, worry, and related emotions?
In any case, yes, there is a lot of storytelling covering the baggage everyone feels. However, I can't recall a single scene in which such attempts are the overall source of problems. If anything, those seem more like a Focus or Direction. I say this because it is something of which the characters seem keenly to be aware and trying to manipulate.
That said, what everyone wants regarding the activities of superheroes is definitely a source of issues and conflict. This comes from your "peace of mind" examples, and even accounts for the feeling that the Accords should be involved. As such, there is a plot of the Desire of Physics (Obtaining), or a theme of the Desire of Doing (Experience), or maybe both. Experience is meh, but I like Obtaining:
- Giving Up versus Keeping one's freedom. - Wasn't this the whole reason for the fight?
- Going after Bucky. - Basically made Cap vs Tony because of government against it.
- Destroying a Team - Would there have been a fight if the team didn't care in the first place?
- Freeing the "Prisoners" - This threw the final wrench to produce the climax.
Now, the above is actually a result of my own analysis. Overall, it appears that the OS Concern is Obtaining. Thus, the Story Goal is Obtaining, but Obtaining or Losing what? Well, who's doing the pursuing in this movie? Cap is after Bucky. Tony is going after Cap (sort of). Zemo is after revenge. Two of these pursuits (Cap's and Zemo's) are, from the perspective of someone who has not seen the other Captain America movies, presented very much like revenge in both cases. So, the Story Goal, then would appear to be to Get Revenge.