Difficulties (put these IN ORDER):
What are Extra+, Ultra+, and Ultra++?
Extra+ is something you would more call an Extreme than an Extra or Expert, roughly around high 5* - low 6*.
Ultra+ would be the difficulty above the Ultra diff, usually sitting around low 7*.
Ultra++ goes infinitely onwards from Ultra, covering more and more gaps above, going into 8, 9, 10* etc. territory.
I've noticed a mistake! Who do I contact?
Contact Hydria or Antalf via the osu-web chat.