You need to localize correspondence into a language that is unavailable in the Pega language...

To localize correspondence into a language that is unavailable in the Pega language pack, you can create the Translation rule manually and include the rule in the application ruleset. A Translation rule is a rule that defines how to translate text from one language to another. You can create a Translation rule manually by using the Create menu in Dev Studio and selecting Rule > Integration-Resources > Translation. You can then specify the source and target languages, the text to be translated, and the translated text. You can also use a decision table or a connector to provide the translated text. You must include the Translation rule in the application ruleset so that it can be used by the application. References: https://community.pega.com/knowledgebase/articles/integration/86/translation-rules