SDC: StructureDefinition-sdc-dataelement-notes
Language and translations
In some environments, it may be necessary for a questionnaire to support multiple languages. The rendering tool would select the appropriate language based on a configuration setting, or perhaps would display all available languages and the user would read the one they are familiar with. Systems MAY choose to provide support for identifying language and translations. If they do, they SHALL do so using the generic translation extension FHIR defines: http://hl7.org/fhir/StructureDefinition/translation
These extensions can be used on absolutely any string element on Questionnaire, ValueSet or any other resource. The base string should be the primary language of the questionnaire. It is what will be rendered by systems that do not support the translation extension or by systems whose language preference is other than one of the languages provided.
The ISO 19763 specification permits declaring language on questionnaire titles, descriptions, display names for codes and many other strings. It also supports capturing multiple variants of these strings with distinct languages. These capabilities can be mirrored using the above extensions.