The mormon church claims many converts in Mexico, Central and South America. Outside of the US, the largest populations of mormons are in Hispanic areas of the world. Mormon non-scriptural publications are translated into Spanish and Portuguese, mainly because that is the most needed language outside of English.
But, it should be noted, the retention rate of these converts to mormonism, how much they actually participate in the religion once converted, is very, very low.
These religious groups (not just mormons) target poor, undereducated, Christianized populations. It is easier to convert someone from from Catholicism or other Christian beliefs than it is to convert non-Christians. With non-Christians, you have to convince them of the truth of Christ. Christians who already have this belief only have to be convinced that the missionary is telling them a “better” truth than the one they already know. With mormon missionaries, it is a trained and polished sales pitch.
Also with mormonism, they claim to be the one true Christian church, thus, they see their proseltyzing mission as one of converting everyone to “true” Christianity. Including Catholics and others of the Christian faith.
The same thing is happening in some African countries (Ghana comes to mind).