But the numbers still don't favor a commercial Spanish CCM to go up against an already existing non-commercial Spanish CCM.
I don't think anyone is expecting Amor Celestial to wind up on 93.3. Wouldn't rule it out completely, but extremely unlikely. It was already tried on KLAT and didn't last long.
Radio Nueva Vida is much more likely. Non-commercial service from a huge religious broadcast organization, which I don't see ignoring one of the largest Spanish speaking markets in the U.S.
We know that the CIA was actively encouraging and in some cases even funding missionaries as a way to keep tabs on rural regions and to suppress the spread of communism.
I think those missionaries were already against Communism without any CIA influence. Communism has generally been anti-religious, as it saw churches as tools used by the traditional power elite to create a compliant populace that didn't question the existing order of society. Missionaries and Communists have long been pulling at opposite ends of the rope.
Liberation Theology, which aligned with Catholicism, was viewed as a threat and several tactics were used to undermine it before it brewed communist sentiment.
Liberation Theology was always a small subset of Catholicism and was harshly criticized by the upper hierarchy of the Catholic Church. However, many in the mainline Catholic Church were strong critics of repressive regimes who felt those governments were working against the best interests of most of the people. Those critics often paid with their lives, but they were not Communist sympathizers. They just wanted a better life for the people.
The protestant spread wasn't completely organic as it was once believed to be.
There are a lot of people who feel their "traditional" religious affiliation isn't meeting their spiritual needs and are willing to go in a different direction. Perhaps Evangelical Christianity fills that desire? Look at how mainline Protestant churches in the U.S. have been bleeding membership for decades, while Evangelical churches flourish. Why would it be any different in Latin America in regard to the Catholic Church? I already mentioned the example of Brazil upthread.
there is even evidence that Trans World Radio received funding to help counter communism.
Having been a shortwave listener for 60 years, I am well familiar with Trans World Radio. I have never, ever heard any suggestion that TWR received CIA funding for anti-communist programming. I'm sure that many who donated to TWR and other such broadcasters saw evangelization as a way to help counter Communism, but some government grand plot to pull people away from Catholicism? Not buying that.
I just think it is important to note why there is a difference in religious preferences between Mexicans and the rest of Central America for the purposes of radio.
Mexico long suppressed religious broadcasters in that country, while other countries allowed them to operate freely. How much that has to do with the split between Catholics and Evangelicals is anyone's guess.