Even on old Gibbed, you couldn't change a flag on a current play, you had to change it for the next play. Meaning, if you changed the "Intimidated the Fan" flag on an ME2 save, it wouldn't effect the story until you started an NG+ run, I know this because I did it many times, along with adding resources to not have to mine as a time waster. As far as the flag goes, it is a ME1 issue, as I was able to look at my new MELE 1 save and see the flag set wrong, and make a change in it. Now sure this one if fked, but IN THE FUTURE, if you wish to make a change, you have the option.....IF you wish too.