Well if we want to go that route...Cuba should be added with Che Guevera as their leader. They would get a UA for spying, increasing success rate by 50%. Science and growth is increased by 25% while empire is under 3 cities
Why as their leader? In Cuba Guevara was just Castro's hired thug, his most notable "achievement" the establishment of a particularly effective gulag system used to incarcerate political prisoners and unpopular minorities. He joined the revolutionary movement after it was formed, and was among the candidates to be chosen as a leader following its success, but was neither its formative member nor its sole important player.
Certainly Civ shouldn't stray away from unpleasant leaders, but Guevara wasn't a leader in any sense, in Cuba or elsewhere, and most Civ choices have a better claim to fame than "someone who was good at having people tortured".
This is where Che Guevera comes in. He wanted to be a doctor and travelled all of south america and latin america. He noticed that everywhere he went, people were poor, miserable, and working for white corporates. He noticed that being a doctor would only be treating the symptoms of suffering. The only way to cure the disease would be to liberate the countries from foreign rule. So he began his crusade in Cuba and freed them from capitalist rule. Ever since then, Cuba has had the highest eduction rate in all of the Americas (Over us too) and free healthcare among other perks and survived the many attempts we made to (passively) destroy them.
Sounds like you've obtained your info from one of the films glorifying Guevara. Yes, he wrote a book as a student radical. Pol Pot started life as a Buddhist monk. And in positions of governance both with known for little more than largely meaningless brutality that achieved nothing - Pol Pot with Khmer Rouge purges fuelled by paranoia, Ernesto Guevara both with the pogroms he instituted when taken on by Castro and as leader of his revolutionary movements, with his tendency to randomly shoot people he deemed not loyal enough to his cause, sometimes en masse.
For all his rhetoric, Guevara achieved essentially nothing in any country he visited other than starting unsuccessful rebellions that got a lot of poor, oppressed people killed. Not infrequently by Che Guevara himself.
More appropriate leaders for Cuba would be Carlos Manuel de Cespedes (who successfully obtained Cuban independence from Spain), Jose Marti (not actually a Cuban leader, but the leading voice campaigning for independence and today considered Cuba's national hero), Fulgencia Batista (who instituted progressive reforms as Cuba's first democratically-elected president) or, of course, Fidel Castro.
As for independence from the US, this was granted by Theodore Roosevelt, who would make a decidedly odd choice of Cuban leader...
Now why the UA? Cuba completely owned America during every attempt they made to destroy them.
Which is relevant to the proposed overdone UA how? Cuba's not known for its intelligence operations (though a bonus to counterintelligence might work, spy actions already have such a high rate of success against most targets that it would barely be useful), and indeed has long been known for its poor economy and use of antiquated technology precisely because of the trade embargo against it. The growth bonus might work.
1. America declared a trade embargo against cuba after they earned their independence solely off the fact they did not have free reign over cuban resources anymore.
Just think, it only took them 60 years (Cuban independence: 1902. US sanctions against Cuba: 1962, in response to the formal abolition of democracy). Almost long enough to think the two events might not be related...
I suppose recent sanctions against Mali following the coup there are a response to the Malinese restricting export of their goods to the West?
They thought it would cause the people to starve and eventually overthrow Fidel but other Communist countries around the world helped Cuba survive and it royally pissed off america to know that they couldn't bleed them out peacefully.
Additional diplo bonus for civs that adopt the same social policy branch?
America has forsaken all claims to Cuba since. They understand they can't take Cuba without making themselves look like royal asses to the rest of the world.
Cuba should be in it. Che should be their leader even though it is Fidel. Che was the reason the rebellion ever began.
I think you should read up on both Cuban history and that of Ernesto Guevara. Not that this is in any way related to whether or not Cuba should be in Civ, but as a minor island nation whose main claim to fame is as a pawn in the power struggles between major nations (first America and Spain, later America and the Soviet Union), it's probably best represented by Havana as a city state (with cigars as the unique luxury, naturally...)