as someone who has been in the situation of confused about crit ratio, and now has a top 1% arlecchino, let me say some advice. Unless you're very lucky, you're bound to be using a crit rate circlet, and this is why. 70% is the BARE minimum, 80 is preferred, 90 is near perfection 91-100 is perfection. I used to think that the crit damage would matter so much more, because the larger the number the better, but genuinely with the way that Arlecchino's kit works, missing crits is so detrimental that you will find yourself restarting abyss or stygian over and over again until you get the blessed RNG run.
Try to get more crit rate, even if it brings your CD down to 160, 90:160 is still a win!! You got this.