not sure to be honest, unrest was never researched by anyone. The only post I know of is this oneEnPhreg wrote:one concept i didn't understand is the effect of the 'bonus to unrest threshold' for buidlings. what effect has a positive or negative value?
viewtopic.php?f=178&t=2316
but iirc unrest bonus is only used when randoms events are on to allow rebellions.