I don't have enough info to make a guess other than making a hit on a head of state isn't for amateurs, even against the President of Haiti. He had to have at least a few guards on his protective detail. I wouldn't rule out Venezuela either, as they and Cuba are known to assassinate key figures. It's also possible the security detail let them into the residence.
The Dominicans share the Island. If you think it was Cubans, do you think the Dominicans let them in on yheir end?
I don't have enough info to make a guess other than making a hit on a head of state isn't for amateurs, even against the President of Haiti. He had to have at least a few guards on his protective detail. I wouldn't rule out Venezuela either, as they and Cuba are known to assassinate key figures. It's also possible the security detail let them into the residence.