Well... guess you'd have to examine your save file, i noticed i had the flag a while back but thought nothing of it, figured it was for some minor text variants regarding Chika, turns out that was the case but suddenly it's a really important flag. The main way i guess you'd find out is by being smart and keeping a backup save in another slot between patches and if you end a new patch with a missed scene, go hunting through the .rpy files and look for an 'if X=true then skip' or come to the thread and ask/check if it's been brought up. I figure some of the more code minded players probably know faster ways to identify these sorts of things but you'd have to ask them.