Client Localization regional variations

We are setting up new system to use the new translation manager in 7.7.1 rc3. We are trying to use the Spanish (Colombia) regional variation but the ISO 639-1 code for this doesn’t work (es-CO) if you just use the (es) code it doesn’t load any of the translated values. It work fine via the language switcher control but were are using the command in script system.util.setLocale(‘es-CO’). What am I missing here?

I was able to replicate this. I’m not sure exactly why it’s happening (other than we didn’t focus much on the regional variations), but I’ll make a ticket.