When trying to use the "Reveal HR" or "Open" feature in Xinet CM (Google Chrome extension), it does not reveal the file in the Finder or the application. You have confirmed that your AFP volumes are mounted on the Mac.
The problem does not occur when using the same browser version and same Xinet credentials running more recent macOS versions such as 10.14 Mojave or 10.15 Catalina.
Xinet CM is not compatible with macOS 10.12 and macOS 10.13. You will need to upgrade to macOS 10.14 or higher in order to be able to use this feature as it has been solved in the latest version of the mac.