I am not in Argentina, but I have head about people who have sent their children to study there in SSPX schools.

I have found information about three of these schools:

Source: https://fsspx.news/en/schools

-Escuela del Inmaculado Corazón de María
Ruta 5, esq. Bosque Alegre
Va. Montenegro
5189 Anisacate
Córdoba
Argentina

Escuela primaria para niñas
Colegio para chicas


-Escuela Santo Domingo Savio
General Bartolomé Mitre 268
5501 Godoy Cruz
Mendoza
Argentina

Escuela primaria para niños
Escuela primaria para niñas


-Escuela del Niño Jesús
Calle Sucre y El Maestro
1744 La Reja
Buenos Aires
Argentina

Escuela primaria para niños
Escuela primaria para niñas
Colegio para chicos
Colegio para chicas
Escuela secundaria para niños


I don't know what a K12 is, but if it means a school for children under 12, I guess that "escuela primaria" probably means the same.

Right, in the US 12 is the last grade in high school.  I saw that info on the SSPX website, but was hoping to hear from someone in the area for further details.