Wanted to check and verify that it was still not possible to edit and existing template.
If so, that’s a real shortcoming that should be changed. And, the template edits should globally update on the pages that were made with that template.
Thanks for writing in! Are you referring to the existing default templates or the existing custom template you have created with the Cornerstone Builder? You can always edit your custom templates created with the Builder. It will also automatically change all the post or page that uses that layout template once you have saved your changes.
Which custom template? The one created with the Cornerstone Layout Builder or the template file you have added in your child theme? I would recommend that you create your own thread so that you can also post your WP Dashboard log in so we can easily check your site.