Child-Themes will now be considered for inclusion into the WordPress Extend Themes repository.
Note: Child Themes are not currently being considered for inclusion in WordPress Extend.
Please be sure to read the Theme Review process and guidelines; also, please note the additional Child-Theme guidelines before submitting a Child-Theme for consideration.
Please note, although at the time of this writing the upload script may note the Child-Theme “fails” as the criteria used for Child-Themes is slightly different. If the Child-Theme did actually pass you would see at the bottom of the upload acknowledgement page a reference to the new Themes TracTrac Trac is the place where contributors create issues for bugs or feature requests much like GitHub.https://core.trac.wordpress.org/. ticket as well as receiving an email referencing the ticket as well.
You will also be able to check the open status of the Child-Theme in this Trac report: https://themes.trac.wordpress.org/report/6