I think the numbers must be wrong.

you only need 120 for no chance of reappearance.

factions will only have a chance of coming back if there is a rebellion in one of their former provinces which means below 100.

if they do come back, if any former provinces of theirs has less than 120, it has a chance of having a reappearing stack spawn there also.

Thus, with 120 loyalty, there will be reemergences in that province.

Note: if playing VI, just activate autotax and you get 120 adjusted automatically.

lot less microing.