Sets the KINDOO invitation email for a given language that is sent to a user that does not yet have the KINDOO application and is flagged as temporary. If email subject and body are set to empty for a given language, the English saved version will be used. If the English saved version is empty, the email saved by KindooSaveSiteInvitationNewUserEmailByLanguage endpoint will be used. If that is also empty, the default KINDOO email will be used.