1) Parent themes of child themes that are developed need to be made child-theme ready; proper use of where to find files with get_template_part, get_stylesheet_ and get_template_ functions.
2) https://codex.wordpress.org/Child_Themes documentation is applied as part of the theme review process when checking child themes, all information is to be considered good practice and required, with addition to the theme review representation of license information.
3) Parent themes of child themes submitted must have passed the current theme review guidelines for the current revision of WordPress, not if they have passed before, but specifically with the current revision of WordPress.
4) Child themes are reviewed with the parent theme; must pass current theme review guidelines and associated child theme documentation.
5) Recommendation to use the parent themes repository slug as the prefix to the child theme’s name. ex. easel-highsociety, atahualpa-wired, this is only the name of the theme & directory name of theme in the zip, not where to find the theme; even as found in the https://codex.wordpress.org/Child_Themes being part of the review process, this naming convention will stay a recommendation; however, declared best-practice.
6) Description in the style.css must clearly state that it is a child theme example: “This is a child theme for the Easel theme.” – This is for redundancy of recognition that it is a child theme, even though other things will be noted on the repository that it is a child theme, this is for the wp-admin -> themes page for the end user.
Additional For Developers:
1) It is the responsibility of the developer of child themes to keep their child themes up to date with the current revision of their theme that is updated. If a developer make changes to the parent theme, it is the developers responsibility to keep the child themes updated as well.
Changes, word usage, additional guidelines and protocols, as well as information regarding use of child-theme tag requested as part of this discussion.