TLDR: no. When in doubt, don't press "enter comment".
Couple of things...
After considering the tone of comments I've made after the fact, I wonder if the community considers what I've written as unkind, and if I need to rethink my wording (I'm often quite blunt).
Self-criticism isn't a bad thing, far from it. But I'm not sure being able to see flags would be the best way to do it. Flags, after all, are cast by a couple users; if you want the community's opinion, I think the best way to do that is post a sample of those on the per-site Meta and ask "am I crossing a line? How could I rephrase that?".
This will allow people to give you far more insight than a generic flag reason, and will also make it more visible to "the community" (rather than waiting for the couple users mentioned above).
All in all though, if you already think your comment might be seen as unfriendly, either trim it down or, if you can't, don't post it. Better to avoid misunderstandings...
or the user that lodged it (although for the latter, it may be interesting to see their rep, rounded to the closest power of 10).
No. Rep or no rep, any user can appreciate the rudeness of a comment the same. Rep is supposed to reflect how much the community trusts you and how you understand it, sure... But the Code of Conduct does not vary with it. Either be nice, or go take a walk.
The only major downside I can see is it may cause an uptick in Meta questions around the topic, but discussion is always good.
Sure, constructive debates are healthy and I'm more than willing to think some people would like to improve the quality of their comments and be ready to do that in a polite way. But I happen to have been on the net recently and... I do think there would be more people engaging in pointless, eternal rants about "c'mon that wasn't abusive you guys are overdoing it", not appealing for discussion.
I trust the former to be able to learn by themselves or by other means (chat, checking their comments...). It's not worth inviting all the other troubleshooters to the party.