If you add an implementation name , i.e. file/uri/test1 to the VFC , and then use that VFC in a service the implementation is formatted like this -> 

      interfaces:
        Standard:
          create:
            implementation: Artifacts/Deployment/WORKFLOW/BPMN/file/uri/test1

If you open Edit Operation UI from the service it shows the implementation as file/uri/test1

If I rename the implementation in the service to file/uri/test2 , it will format correctly in the template.

    interfaces:
        Standard:
          create:
            implementation: file/uri/test2