For anyone still following this... I hope this is the finished product. Note I did change some field types...

var number CFD = ToDays([Assigned Finish Date] - Today());

var number Dur = [Calc Duration];

var number PC = [% Complete] *100;

var number SD = ToDays(ToDate([Start]) - Today());

var text Red = "#f75d59";

var text Yellow = "yellow";

var text Orange = "#fda302";

If(

$SD < 0 and $CFD < 3 and $Dur <= 10 and $PC < 50, $Red,

$SD < 0 and $CFD < 3 and $Dur <= 10 and $PC < 70, $Orange,

$SD < 0 and $CFD < 3 and $Dur <= 10 and $PC < 85, $Yellow,

$SD < 0 and $CFD < 5 and $Dur <= 20 and $Dur > 11 and $PC < 50, $Red,

$SD < 0 and $CFD < 5 and $Dur <= 20 and $Dur > 11 and $PC < 70, $Orange,

$SD < 0 and $CFD < 5 and $Dur <= 20 and $Dur > 11 and $PC < 85, $Yellow,

$SD < 0 and $CFD < 10 and $Dur <= 30 and $Dur > 21 and $PC < 50, $Red,

$SD < 0 and $CFD < 10 and $Dur <= 30 and $Dur > 21 and $PC < 70, $Orange,

$SD < 0 and $CFD < 10 and $Dur <= 30 and $Dur > 21 and $PC < 85, $Yellow,

$SD < 0 and $CFD < 30 and $Dur <= 90 and $Dur > 31 and $PC < 50, $Red,

$SD < 0 and $CFD < 30 and $Dur <= 90 and $Dur > 31 and $PC < 70, $Orange,

$SD < 0 and $CFD < 30 and $Dur <= 90 and $Dur > 31 and $PC < 85, $Yellow,

$SD < 0 and $CFD < 35 and $Dur > 90 and $PC < 50, $Red,

$SD < 0 and $CFD < 35 and $Dur > 90 and $PC < 70, $Orange,

$SD < 0 and $CFD < 35 and $Dur > 90 and $PC < 85, $Yellow)