The documentation claims that, in version 0.0.5, JENKINS_HOME/*.xml will be synced. However, in JenkinsConfigScmSyncStrategy.java the pattern is:

    private static final String[] PATTERNS = new String[]{
        "config.xml",
        "hudson*.xml",
        "scm-sync-configuration.xml"
    };

This excludes the configuration files for many plugins which are not prefixed by 'hudson'.