I know there isn't button to do that, but is possible in the future the forum have that feature?
Because I've mistakenly reported my post to a moderator by accident.
I doubt that is possible on the SMF software and it's not a common situation for one to mistakenly send a report. You need to click two buttons to send a report, one after you click "report to moderator" and another when you click "submit" after writing a comment or not.
It's unlikely that many users would find themselves there and such an option would be seldom used.
So far, I reported 3 posts with 100% accuracy, 1 of the 3 reported is my post. I don't know how that 100% comes, because my post i did report some time ago, maybe still be unhandled or hasn't been seen by a moderator. (It might also a bug percent calculation)
You can see if you have an unhandled, good or bad reports when you try to submit a new one.
It's possible your reports are aggregated to give 100% accuracy.