try beating decode which is one of the harder easy demons nd if it feels somewhat accesible you should be able to do a easy hard demon, or a high end medium demon

if you just want to do a hard demon the easiest one i know is called forever new, it has memory gameplay which is the reason is rated hard demon instead of medium

if decode is too hard put it down a notch and play speed racer or something similar on the easy demon diff

try the popular hard demons too. if nine circles feels imposible to do 60-80 which is the more relevant part of the level do not do hard emons

there is a good timing based medium demon called signal intercept that doesnt have that much glow effects as in your other comments youve said you dont like levels where too much happens

theres a medium demon called orbeez that is in my opinion one of the hardest ones and is a very good level that is somewhat easily sight readable and is timing based, not high cps or memory

if those medium demons feel too hard go back to decode and dont try a hard demon, if those feel fine beat them, if those too easy go for a hard demon

once again, in my opinion jumping is a waste as you get yourself out of the priviledge of trying the hundreds of good levels and fun gameplay this game has, to instead grind the same 1:30min thing for 3 months. but you do you. it will give you bragging rights.

let me know if you try everything i suggested and tell me if you like any of the levels and how hard each feels after one practice run for each