Well, from what I can see in the editor, they can't build either. Other things that I noticed: The Australian and Canadian Shipyards have the "Reduces Corruption" flag checked in the Wonder box. Didn't that make them pretty much unbuildable? If so, shouldn't it be the flag in the Improvement box that's checked? Same goes for the Naval Station. That may be a deliberate decision on your part though, to stop human and AI from building it, while preplacing it in several spots (I noticed one in Montevideo). Also, many of the unit-spawning wonders (Askari Barracks, French West Africa etc.) do not have the "militaristic trait" flag checked. Is that on purpose? I don't remember if militaristic civs get a discount on wonders - IIRC it's only on improvements. And, last but not least, the Chinese town of Erenhot has no Colonialism resource underneath itself, making some Colonial improvements unbuildable there.