No, I made a mistake here. Although the function works, the AI still detects the increase. I think this is because the owner is a neutral player. Therefore, I see only one way to fix it: remove all buildings initially and build them upon capturing the town:

for build = TOWN_BUILDING_DWELLING_1, TOWN_BUILDING_DWELLING_7 do
  SetTownBuildingLimitLevel('houseInferno', build, 0)
end

function CaptureTown(p_owner, n_owner, hero, object)
  for build = TOWN_BUILDING_DWELLING_1, TOWN_BUILDING_DWELLING_7 do
    SetTownBuildingLimitLevel(object, build, 2)
    for i = 1, 2 do
      UpgradeTownBuilding(object, build)
    end
  end
  local week = GetDate(WEEK)
  SetObjectDwellingCreatures(object, 16, 35 * week)
  SetObjectDwellingCreatures(object, 18, 34 * week)
  SetObjectDwellingCreatures(object, 20, 18 * week)
  SetObjectDwellingCreatures(object, 22, 10 * week)
  SetObjectDwellingCreatures(object, 24, 7 * week)
  SetObjectDwellingCreatures(object, 26, 4 * week)
  SetObjectDwellingCreatures(object, 28, 2 * week)
end

Trigger(OBJECT_CAPTURE_TRIGGER, 'houseInferno', 'CaptureTown')