I submitted 3 screenshots of my Raid gallery which easily exceeds the threshold of 16000+ points for the "S+" appraisal. Yet, the appraisal is only rating the account as an "S" only.
According to the"Event Rules":
Ultra Rare Hero - Red Quality 1 unit 5000 points
Based on that, my account's 3 red mythicals alone should be worth 15000 of the 16000 points required for an S+ appraisal and any 4 additional legendaries would push it over the threshold. Further, as you can see, I have more than enough Legendaries to reach that threshold in EACH of the screenshots.