Cool post!
I prefer the Build-in-Place method. This game is about realism, and I really don't see them doing it any other way. Souldbound wants crafting to be an experiences, so I doubt they would do a Build-And-Place.
That being said crafting most things shouldn't take a millennium to accomplish. Or else a similar situation with shipbuilding in Vanguard Saga of Heroes comes to mind.
Of course your character as AI might be able to continue working on the project as your away, perhaps with less efficiency so I guess the same sort of problem wouldn't exist.
My separate question is based on the Environment and it's relation to buildings.
Could I create some sort of Hrothi Architect/Quarrying/Stonemason guild but as a Janoan, and then have Hrothi build buildings accessible to Janoan's, in a Janoan environment? I guess what I'm picturing is stone houses in the Jungle. Do you think that's possible? It would require some deforestation.
I guess what I'm getting at, is how much do you think environment will effect the ability to import different architectural culture to another environment.