How to install a new language

I have the .po files corresponding to the new language I want to add, however when I add them to the {bonita_home}/platform/work/i18n the studio does not recognize the language.

Furthermore, the new locale appears when using an API call to show all current locales and there's an option to switch to that language in the BPM Portal HOWEVER when passing through forms the messages are still in english even when having, on the url parameters, &locale=pt_PT