API to get an email template

Can the API access the Email templates like "Studio / Text Editor / Email Text / email_content.template.mentions.text"?

I understand that we cannot create custom triggers for these emails from an external app, but is there an API I can use to get the template (hopefully localized) so that we can send the email from an external service.  We would do all the text substitution on our end, we just need to pull down the template.

Best case scenario:

• create an endpoint on Lithium
• pass in the variables that would be used for text sub into the endpoint
• use endpoint freemarker to get the needed template
• use endpoint freemarker to perform text sub
• return the localized email from endpoint to our external app