You're referring to the difference in spelling, "Anna" versus "Ana?" It's definitely a reference to the Mexican general Santa Anna. It's a humorously casual and disrespectful description of a bit of history. He's describing it the way you'd describe some bit of regional history that you learned in elementary school, that you're supposed to know, but don't remember very clearly. The name Santa Anna is famous enough that a U.S. reader would be prepared to recognize it. He was the Mexican general whom the Texans fought against in the Texas revolution, "at the Alamo" and in the Battle of San Jacinto. I can't account for the apparent spelling error. It's interesting. Perhaps the spelling actually varied. Perhaps it's a typo, perhaps Kingsolver goofed, or perhaps it's an accurate period detail. The woman's name that's spelled "Anna" in English is "Ana" in Spanish. The mother of Mary, "Saint Anne" in English, is "Santa Ana" in Spanish. It wouldn't surprise me if Santa Anna in the general's surname preserved some older or variant spelling... much as one occasionally runs across a "Smyth" or "Smythe" instead of "Smith" in U.S. surnames.

It refers to the general.