I’ve discovered the documentation where one can translate custom email templates by using user metadata.
Auth0 needs another mechanism where custom email translations should be based on browser language settings. For example, if I create a Password reset request from a Chinese AuthLock or Universal login, then it makes sense to adopt some kind of flag to detect the language of that request, which can then be used in the template to render the correct language.
Also, how does someone translate the subject of a custom email template?