Since developers are going to add more tiers, I would like to suggest difficulty's names on them.
T7 (Expert) - Technically harder than Insane, like more timing prediction or more skills to beat a map.
T8 (Challenge) - For a map that takes the accuracy of timing and some inhuman skills.
T9 (Exhausted) - The name tells it,
REEEEEEEEEEally takes so much time, timing accuracy, inhuman skills and/or long map, causing you to run out of energy.
T10 (Diabolical) - Credit to Boshy for the name. For a map that beyond humanity, such as
LOOOOOOONG wallpogo, almost perfect timing accuracy, downpogo into random bounce/bhop, etc.
You guys can suggest any names of them, this is just my opinion.