I knew that because I developed my own campaign in this way, from 6 provinces to the current 76. In all the steps the map was functional.

Regarding the victory condit¡on, the question of 15 or 50 provinces comes from the selection made in the last imperial campaign. So if you want the short campaign, you must select imperial campaign, set the new victory conditions and it will be automatically set in the provincial campaign.

I am not sure what happens with the second condition: destroy or survive to other faction(s). This could be a problem when some factions are eliminated from the campaign.

There is another wrong requirement: the need for a Latium region and a Rome city for the campaign to work. Yesterday I prepared a greek map without that region and settlement and it works, at least for 6 turns. Again this could affect to the victory, as the requirement of taking Rome cannot be fulfilled.