Registering custom posts is a plugin territory. It means that you need to remove them from the theme’s functionality and register them via a plugin (usually recommended when installing the theme using TGM Plugin Activation or something else). Here are the recommendations of the Theme Review Team.
Themes must not incorporate the following, Plugin-territory
functionality. This list is not all-inclusive.
- Analytics scripts
- SEO options (meta tags, page title, post titles, robots.txt, etc.)
- Content Sharing buttons/links
- Custom post-content shortcodes
- Custom Post Types
- Custom Taxonomies
- Removing or modifying non-presentational core hooks
- Disabling the admin toolbar
- Resource compression/caching