Hi,
The editor being used for HTML templates is the one set as the default editor in your Joomla Global Configuration.
However, I would like to inform you that the future of Acymailing lies in the drag & drop editor. We strongly recommend taking some time to familiarize yourself with it to fully utilize the features and benefits it offers.
We understand that this transition may come with some questions or uncertainties. Please rest assured that our team is here to assist you promptly. If you have any queries or require any support in understanding the drag & drop editor, please do not hesitate to reach out to us.