Since Puerto Rico is part of the United States (Commonwealth). Does San Juan have an English radio station besides AM 1060 WCBG and AM 1190 WBMJ? Also, is there any NPR stations in Puerto Rico?
I think that you mean 1030 WOSO in San Juan, a news talk station. WBMJ is all religion, and co-operated with WCGB 1060 in Juana Díaz (a Ponce market municipality) and WIVV on the island municipality of Vieques off the SE shore of PR.
WIPR AM and FM are owned by the Commonwealth government, and have had an NPR relationship primarily for news, but I do not think they have even that now (the website shows affiliation with NPR, The Met Opera, RTVEs, and Radio Netherland) but the program grid shows very little. WIPR FM is classical and the AM is talk, news and Puerto Rican music.
The reason why there is not any more English language programming is just like the reason why New York City does not have a country station... not enough potential listeners.