I’ve just added on the file you posted Spanish and Portuguese cultural connections, as well as some British Commonwealth connections. I will add more soon.
Regarding the MIA/BOS issue, the map shows the area around correctly, the population data is the only problem I think.
For the Caribbean, I think you should start by increasing demand to/from PUJ, MBJ, SXM, AUA, CUR, GCM, CUN, STX, and BGI off the top of my head.