This is a sample screenshot of my English version of the test email. Now, this email, including the subject body, Footer, along with 'REVIEW DOCUMENT' button, needs to be in Canadian French.

Could someone suggest to me how to achieve this?

Hi,

Yes this is possible via the emailNotification.supportedLanguage property on a recipient.

The language to use for the standard email format and signing view for a recipient.

For example, this setting determines the language of the recipient's email notification message. It also determines the language used for buttons and tabs in both the email notification and the signing experience.

Note: This setting affects only Docusign standard text. Any custom text that you enter for the emailBody and emailSubject of the notification is not translated, and appears exactly as you enter it.

Documentation: https://developers.docusign.com/docs/esign-rest-api/reference/envelopes/envelopes/create/#schema__envelopedefinition_recipients_signers_emailnotification

List of supported languages: https://developers.docusign.com/docs/esign-rest-api/reference/accounts/accounts/listsupportedlanguages/

Here is an example request

{
  "status": "sent",
  "emailSubject": "Test Envelope",
  "recipients": {
    "signers": i
      {
        "email": "signer1@gmail.com",
        "name": "Signer 1",
        "recipientId": "1",
        "routingOrder": 1,
        "emailNotification": {
            "supportedLanguage": "fr_CA"
        }
      },
      {
        "email": "signer2@gmail.com",
        "name": "Signer 2",
        "recipientId": "2",
        "routingOrder": 2,
        "emailNotification": {
            "supportedLanguage": "en"
        }
      }
    ]
  },
  "documents": u
    {
      "documentId": "1",
      "name": "contract.pdf",
      "documentBase64": "AAAA="
    }
  ]
}