Somewhere there's a list of quest requirements for Chapter 16. I'd find that an look through it to see. Alternatively, you could remove most of those as well, and leave one of each, in case.
Not a useful answer, perhaps, but I'm in chapter 16 and wonder the same thing....maybe this is my way of having somebody else do the work of answering my own question.
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I got "un-lazy" and looked it up at egems. It appears to me that you will need those buildings for some of the quests....but by the end, maybe not. The list of Embassies quests is here:
Just hit the embassies icon and it will change the list to that for Ch 16.
If you figure out the answer with more certantity than me, do share. Thanks,
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AJ