The CORBA ORB must be aware of the transaction service mode and configure accordingly. Where the TS is running in JTS mode, the ORB must include calls to the JTS initializers in its startup. Contrawise these should not be called in JTA mode. However, the TS service startup depends (when in JTS mode) on the ORB service. This creates a mutual dependency that is not cleanly handled at present. This pattern will likely also affect any other services, including user services, that require CORBA ORB intializers.
Additionally the ORB service provides ("iiop", "orb") whilst the transaction service expects ("jacorb", "orb-service") i.e. is jacorb specific not generic. This dependency is therefore not currently functional, making it impossible to start the transaction system in JTS mode.