I worked on a further edit dialog of the Plone add-on collective.templates today. I added another register to the dialog and reordered some content fields to make it more smooth for the user. You could see some of the register of the template center edit view below.
I published my changes to the Plone add-on and its edit views today. The source code is available from the Plone community Github repository:
https://github.com/collective/collective.templates
The new release is available from https://pypi.org:
https://pypi.org/project/collective.templates/