It is possible to reference a template from within a known contract with absolute reference like ...
... if the target contract is packaged as part of the web application (within the WAR).
But it fails when the target contract is packaged as a JAR.
Since the absolute contract resource reference is supported for war-based target contracts it must also be supported for jar-based target contracts. This allows to extend/customize base contracts without the need to copy all base contract resources to the extended/customized contract. The notation of activating contracts like "custom,base" e.g. in the contracts configuration in faces-config.xml also indicates that such combined contracts are to be supported.
I was able to make such absolute contracts references working with some little changes. But first it must be decided if such absolute contracts references should work by design or must be prevented.