with at least basic design docs for each province,
That'd require people to actually write design docs
I firmly believe that most problems with province mods (or any huge mod) could be solved if people knew what a design doc is and how to use it. At the very least it gives an excellent idea of just how insane a task you're about to undertake. I'm speaking entirely from experience here.
I'll be honest - I don't know how I feel about that much cooperation between province mods. In my mind, once you go that far, it might be more beneficial to just form a single team and get a province done rather than having five teams working on separate provinces but always working around each other. This was a big difference between MW and OB modding (at least until relatively recently): in Morrowind, if you wanted to make a lore friendly province mod, you joined Tamriel Rebuilt. In Oblivion, you started your own mod.
The whole point of working in a team is compromise. You have to give up some of your ideas, but in exchange you get the ideas of others. You also get things done a lot faster than if you were working alone.
Not that I'm against cooperation and coordination between teams, I just don't think that making everyone work around a specific set of rules and constantly work around one another is the best way to get things done.
You all should be aware that because of how TES files are formatted the method used in Requiem for a Capital Wasteland and Morroblivion should still hold true.
It is not legal to import assets from other games into Skyrim, nor is it legal to discuss it.