According to the obituary for Carlos Fuentes in the NY Times:

Though Mr. Fuentes wrote in just about every genre, including opera (a 2008 work inspired by the life of Gen. Antonio López de Santa Anna, the wooden-legged president of Mexico during the Texas Revolution)…

No. Carlos Fuentes did not write an opera, he wrote an opera libretto. José María Vitier, unnamed in the obituary, wrote the opera. Again, the composer goes missing.