Correct; entities are not shared on the cluster through a common cache. There is a cache invalidation framework (CIF), through which messages can be sent around the cluster to invalidate the local caches on each node.
Some of the older versions of the clustering docs actually have better coverage of the CIF than the newer ones. See the Cache Invalidation section of http://docs.jboss.org/jbossas/clustering/JBossClustering7.pdf . In particular, have a look at the "Use Cases" section starting on page 98, where a pattern of having a read-only version of a bean along with a read-write version is described. Perhaps this will help with your use case.