If you are open to use Java APIs, you may want to try something like below to get Routing History,
wt.fc.collections.WTArrayList auditCol = (wt.fc.collections.WTArrayList) wt.workflow.engine.WfEngineHelper.service.getVotingEvents((wt.workflow.engine.WfProcess)self.getObject(), null, null, null);
System.out.println("***Transition Expression: Audit = " + auditCol.toString());
java.util.Iterator auditEvents = auditCol.persistableIterator();
comments = "";
while( auditEvents.hasNext())
{
wt.workflow.engine.WfVotingEventAudit audit = (wt.workflow.engine.WfVotingEventAudit)auditEvents.next();
System.out.println("***Transition Expression: User vote = " + audit.getEventList());
System.out.println("***Transition Expression: User comment = " + audit.getUserComment());
comments += audit.getUserComment();
System.out.println("***Transition Expression: Complete Time = " + audit.getPersistInfo().getCreateStamp());
}
System.out.println("comments = " + comments);