A bit of history:
While talking about Exitosa in New York, the model for all these English language music and Spanish announcers and ads stations is WFID in San Juan.
In 1983, WFID was a Beautiful Music station that was not "winning" in ratings or sales. It was sold, and the new owner hired me to "modernize" it (his term). So we looked at the over-radioed market and first concentrated on sales. 95% of a San Juan significant station's revenue came from agencies. At agencies, the buyers and planners were generally middle class or upper middle class younger women who had gone to bilingual schools.
With that in mind, I created a format based on the single question of "what would a 30-year-old media buyer listen to?" We came up with a format that had "snob appeal" by playing nearly all English AC hits along with a percentage of Puerto Rican pop artists in Spanish and a few Latin American or Spanish singers or groups.
We hired DJs who were of the same background, and who knew how to pronounce the English song titles and knew the music.
WFID sold on that "snob appeal". It was perceived as being a station for those with more spendable income, and had a huge power ratio approaching 2:1.
Like all of Latin America, most middle and upper class kids go to private schools that are bilingual. They like the stations that play English pop music. So when repressive governments (Venezuela, Colombia) or a huge economic downturn (Puerto Rico) drives middle and upper class people into exile, many will find a station similar to what they grew up listening to and use it in their new home.
In markets where there are few upper income immigrants, such a station will not work.
An alternative is the K-Love model in LA, where we combined pop in Spanish, pop-sounding Regional Mexican and a few English language songs to appeal to the narrow but adequate group of listeners in LA. It turned out that there were enough of them that did not want norteña and banda to get us to #1 with a 7 share, but that had much to do with combining a percentage of Mexican listeners with all the non-Mexicans in the market!