It's been disabled because it didn't work. I don't know why everyone wants to play the campaign on the mod.
I want to play the campaign in the mod because I want to fight with Maltese Knights and Swordsmen against Sahin and Lizzy.
In general, it would be a new experience to do the missions with the remade civilisations. Maybe the missions and cutscenes that didn't work could be remade, maybe a new campaign could be made in which you have to win the War of the Triple Alliance with Brazil and/or Argentina? I don't know but that would be really good.