Before Britain took the Island there were Major restrictions on Native Business. [Basically you needed a License from Madrid] which few of the Free Blacks that made up 25% of the Population, or the lower Class White Craftsmen could get.
During Britain's Occupation, They removed all the restrictions on Native Business, During their time there Cuba's GNP almost doubled.
Also The Americans send Factors [with their Families] to set up Shipping offices.
When Spain Returned in 1763, one of the first things they did was send troops around to shut down all the new Business.
In order for Britain to hold Cuba, they need to take it at the beginning of the war and not at the end.
In other words Pitt has to stay in Power, and not be replaced.
England takes Cuba and the Philippines, and Spain Choses to get the Philippines back.
Assuming the Spanish agree to give up Cuba, I think one of their main priorities come the American Revolutionary War would be to take it back. Expect earlier, stronger, Spanish aid to the American rebels in an attempt to weaken Britain.
Close to 2/3 of the Troops the Governor of Louisiana used to take take Florida in the 1780's were Cubans.
Here Spain would have to ship Troops from Spain, and after 12 years of British Rule, they would be unhappy with the Cuba they got Back.
I also think that There would be no 1806 Argentina expedition ITTL, instead Britain would try to retake Cuba.
If Spain fails to get Cuba back in the Treaty of Paris, at the end of the ARW
[I see no way the US can get it] then Latin America become very interesting in the 1800's.
Cuba is is big as England, And Havana has always [Pre Castro] been seen as the Capital of Latin America.
The UK would most likely object to Spain selling France Hispaniola in 1795, and has Cuban troops to use to express this Displeasure.
The UK comes out of the Congress of Vienna, controlling Cuba, Hispaniola, PR, and Jamaica,
The Dominion of the Caribbean is formed at the same time as the D of Canada.
This is a TL I would love to read.