Ok, I got a campaign map working. I made a new custom city model. I edited desc_sm_settlements.txt for the faction's cities to use this new model. I deleted map.rwm in my custom campaign folder.

Boot up game, there's no change.

To test something else, I swapped the "roman" tag with "carthaginian" in desc_sm_settlement. No change. Romans still use roman city model and so does carthage.

Did I miss anything that I should've edited?