Since the RegistrationBase object no longer watches for state-changes via the callbacks, these log messages "Moving on, will re-attempt when Watcher notifies us of a state change" are no longer valid.

At the minimum, these messages should be updated.  Perhaps this "general exception" message should be turned into a class-constant. For the RegistrationBase class it could be something like:

    GENERAL_EXC_MSG = "Received exception. Moving on. Will not re-attempt this command: %s..."

then in the EphemeralNode you could override the message

    GENERAL_EXC_MSG = "Received exception. Moving on, will re-attempt when ..."