Importing the New Locale into Plesk
Place your new locale files in the corresponding directories. For example, the following directories will be used for the Brazilian Portuguese locale on a Linux server:
/usr/local/psa/admin/application/default/resources/languages/pt-BR/usr/local/psa/admin/plib/locales/pt-BR//usr/local/psa/admin/application/admin/resources/languages/pt-BR//usr/local/psa/admin/application/smb/resources/languages/pt-BR/