The Confederacy has no real ability to project power. Basically, it doesn't have the logistics to field an army far from its home bases, and it has no blue water navy and no real ability to build one.
So the notion of Confederate military conquests is pretty far fetched. If the Confederacy goes after Cuba, the Spaniards will kick their ass. If the Confederacy goes after Mexico... well, the Mexicans have done quite well at fighting the French, they'll do better against the Mexicans.
Everything else is simply out of reach - neither the United States nor Britain (especially Britain) will allow the Confederacy to go knocking over Central American or Caribbean countries. And much of the Caribbean is under the control of powerful European states.
It's possible that the Confederacy could inherit conquests from the United States. Say if the US decided to go all in on William Walker's expedition to Nicaragua, and say that lead to the US conquering several central American states. But even there, its dubious, I don't see these territories kept by the Confederacy - no ability to hold it against the Union.