FYI - I figured out where the code was located for the labels and did it manually, so will have to update the code again after any upgrades, but at least it is in the correct language.
/wp-content/plugins/store-locator/functions.sl.php
add the h1=es if you wish. Don't think it's necessary due to Google sees language of browser
/wp-content/plugins/store-locator/js/store-locator.js
changed not found to no encontrado
changed "No results found." to "Lugar no encontrado."
change "Your Location:" to "Su lugar"
changed "Directions:" to "Indicaciones para llegar:" in two places
changed "Mapa" to "Mapa"
Hours: to Horario:
Phone: to Tel:
(search with browser for keywords)
By the way, I couldn't use the MX translation due to the fact I need the ES WordPress translation and I couldn't figure out how to rename the MX to ES. Even so, it didn't affect the problems above I believe.