So it seems like when playing as Chinese civ, you can build both landmarks as a civ bonus, but if I build landmarks from a previous dynasty that I did not build when still in that dynasty, it will roll me back to that old dynasty. So if I was in the Ming dynasty and built a landmark from the Song dynasty, I am now once again in the Song dynasty, even though I can still create units only available in the Ming dynasty. I can’t build the Pagoda anymore, though. I also lost the ability to create another granary, even though I had already built one.
Screenshots attached