Is it possible to sync an AEM email template for a transactional message in Message Center? I don't see documentation one way or another. This would be for a real-time event triggered campaign.
Yes, you can sync AEM template in transactional message by configuring the AEM account in transactional delivery template properties. The steps to configure and Synchronize / Desynchronize is same as how we configure AEM template in normal campaign delivery configuration.
For editing the HTML, If you Desynchronize and Synchronizing the delivery template, make sure to publish the transactional message delivery template.