The translations section of the “Commence a module” guide explains the setup for a new front-end module.

That leads to the i18n best practices documentation to explain the translation process.

The Wiki page How To translate FOLIO has some additional notes for translator teams to use Lokalise.

The FOLIO UX user experience design guidelines have a section Language rules to facilitate translation.

The FAQ for dates and times explains the storage and display.

Note: When using the hosted reference environments, please avoid changing the locale of the entire tenant (in the “Settings -> Organization -> Language and localization” menu at the /settings/organization/locale URL path). Changes here affect all users that are performing tests on the reference environments. Instead, use the temporary session-based locale switch in the developer settings (“Settings -> Developer -> Session locale” at the /settings/developer/locale path).