Does the connector validate documents against local DTDs/schemata or from AEM? Does the connector interact with AEM in any way other than checking out/checking in reading / writing XML in AEM?
The docs doesn't mention both use cases atleast -- https://www.adobe.com/content/dam/acom/en/products/xml-for-experience-manager/pdfs/XML_Documentation...
Adobe CCMS For Documentation Management - Features
That seems to be about the XML documentation product, rather than about the oxygen client. But, it seems like it just uses the local xml catalog.