Regarding Central America? I have nothing specific to offer unfortunately. Most of my knowledge is from Academic journals that I've searched on places like JSTOR. I'm actually looking for history books on Central American history.
Cuba could easily be much better if the post revolutionary period began reforms in the 80s or 90s to lessen the burden of the Special Period, but Cuba was kinda doomed to being middle income since the 20s since its economy was nothing but sugar and tourism, both of which are subject to boom-bust cycles. There wasn't much industry or other major extractive industries like in the Dominican Republic, and that needs to be fixed in tandem with political issues.
As for Dominican history? Where do begin, the country is nothing but missed opportunities.
The best case scenario I think is if the Trinitarios weren't coup'd in 1844, leading to the establishment of a liberal democracy right off the bat. This means preventing decades of political instability, avoiding the re-annexation of Spain (and the destructive restoration war), the precedent for tyrannic governments, decentralization, and most of the money put into the country instead of being robbed by cronies/and or spent on the military. All of the above would lead to population growth, vast immigration who bring in much needed capital and technologies and steady, continual economic growth. By 1900, we could have a place that has a population of say, 3 million instead of 800,000 and a diverse economy firmly seated in the Upper income countries of Latin America. The country would also have superior infrastructure and living standards compared to most of its neighbors in the region. By the modern day, you get something that's at worst Eastern Europe living standards and at best First World.
For the Philippines I was mostly thinking avoiding Marcos (or obtaining independence as early as possible in the 1800s and therefore the ability to obtain more foreign investment easily) and going the same East Asian export economy routes that Taiwan, Korea, Japan and Singapore went on. Not well versed enough to offer any specifics.
As for Venezuela, literally just have it diversify its economy. That's it. Venezuela was constantly crippled by its boom and bust cycles.
Frankly you're asking alot for the DR. Though it would certainly have been interesting, and obviously better.
Olvidaste Trujillo, sin él estaríamos mucho mejor. El intervencion y Balaguer tambien se deberían desaparecer.
Obviously with all that you mentioned Trujillo isn't likely but it is still worth mentioning at least due to personal reasons for me.