Hi,
You can find these topics helpful New Review: Tokens are not being translated in email, Custom tokens not working in some emails.
There’s an email hook hivepress/v1/emails/email_name_here that you can use, and inside it you can define custom tokens like $email['tokens']['my_token'] = .... The exact value depends on the type of email. If the listing object is not included in the email context, you can retrieve it using another existing token and then generate your custom value from it.
Hope this helps