Tomorrow I think I'm going to finally get around to doing my history section in the sheet as well. I know what's going on with Yamatai and I think Voltus and I have a rough idea, but @Mihndar do you want to have some history too?
Specifically, two things popped out to me about your sheet:
"...it contains large minorities of various different races... and small numbers of Tinites."
and
"an extensive spy network to support worker's revolutionary movements in other countries"
Incidentally, mine has the little quip:
"In the past Tin has also vigorously fought to push its faith into other countries, and where they succeeded the converts often rebelled and served as spies for the Tin, which has only thrown fuel onto the fire in this situation."
You can probably see where this is going. I think that we could work something out of this, if you want.
I put that there would be small numbers of Tinites primarily to indicate that very few of them leave your nation, as you said you have very strict immigration and hence I presume emigration policies, but sure. The Kataylans have no religion and no policies surrounding that, and that would lay a groundwork for a lot of conflict in the past if you had been actively promoting your faith, and certainly now with the new government.