The (normative) §6.1.5.2.1 on container.xml says:

The contents of this file MUST be valid to the schema in § E.2.1 Schema for container.xml after removing all elements and attributes from other namespaces (including all attributes and contents of such elements).

§ E.2.1 says:

The schema for container.xml files is available at https://github.com/w3c/epubcheck/tree/master/src/main/resources/com/adobe/epubcheck/schema/30/ocf-container-30.nvdl.

I do not think it is acceptable that the schema file (which is normative per the first quote above) is stored on a repository that is not under the control of the WG. I believe the normative schema should be stored on the WG's page.

The same issue arises for the Media Overlay schema.