If you want a quick and drastic solution, open export_descr_ancilliaries.txt, and find the first entry for architect. Change the squalor value to -x. Now scroll down to Trigger trigger_architect, and replace the code with

Code:
 WhenToTest CharacterTurnEnd
          Condition EndedInSettlement
          and RemainingMPPercentage = 100
          and SettlementBuildingExists >= sewers
          and IsGeneral

         AcquireAncillary architect chance  50
Now any general who spends a turn in a settlement with sewers will have a 50% chance of getting him. If you want the architect to sort out your lack of governors, scroll back up to his list of effects and add "Fertility 1"(remove quotes) at the bottom.

NB-this doesn't change the description given on the tooltip in game. That will still say squalor -1.