Here is the configuration of the frontend template, I used to do in v1:
The problem is when I view an Article in the backend (admin siteaccess), the frontend template is used.
default should not be used for admin interface.
Note, I tried to use site_group (frontend siteaccess group) instead of default but it's not working.
The only way to have the admin template and the frontend template is to use a siteacces (site instead of default). This is not great because you will have to define the same overrides for all the siteaccesses.
I think admin siteaccess should also use ez-design-engine. It will be good for developers if they want to override a template in the admin interface.