A simple way to read track changes from a docx document is to navigate xpath and  manage the result.

WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.load(new File("myFile.docx"));
MainDocumentPart mainDocumentPart = wordMLPackage.getMainDocumentPart();

List<?> revisionInsList = mainDocumentPart.getJAXBNodesViaXPath("//w:ins", true);

for (Object obj : revisionInsList) {
   System.out.println("--------------INSERT----------");
   RunIns ins = (org.docx4j.wml.RunIns) obj;
   System.out.println("Author:" + ins.getAuthor());
   System.out.println("id(position):" + ins.getId());
   System.out.println("Date:" + ins.getDate());
   List<Object> listR = ins.getCustomXmlOrSmartTagOrSdt();
   for (Object aListR : listR) {
      R r = ((R) aListR);
      printRevision(r);
   }
}

List<?> revisionDelList = mainDocumentPart.getJAXBNodesViaXPath("//w:del", false);

for (Object obj : revisionDelList) {
   System.out.println("--------------DELETE----------");
   RunDel del = (org.docx4j.wml.RunDel) obj;
   System.out.println("Author:" + del.getAuthor());
   System.out.println("id(position):" + del.getId());
   System.out.println("Date:" + del.getDate());

   List<Object> listR = del.getCustomXmlOrSmartTagOrSdt();
   for (Object aListR : listR) {
      R r = ((R) aListR);
      printRevision(r);
   }
}

List<?> revisionDChangeList = mainDocumentPart.getJAXBNodesViaXPath(XPATH_TO_REVISION_FORMAT_CHANGE, false);

for (Object obj : revisionDChangeList) {
   System.out.println("--------------Modify Format----------");
   CTRPrChange change = (CTRPrChange)obj;
   System.out.println("Author:" + change.getAuthor());
   System.out.println("id(position):" + change.getId());
   System.out.println("Date:" + change.getDate());
}

A simple method to print revision “text” is the following code:

public static void printRevision(R r){
	Object objInternal = r.getContent();
	if(objInternal instanceof JAXBElement){
		System.out.println(((JAXBElement) objInternal).getValue());
	} else if (objInternal instanceof ArrayList){
		for (int j = 0; j < ((ArrayList) objInternal).size() ; j++) {
			Object objDeleteInternal = ((ArrayList) objInternal).get(j);
			if(objDeleteInternal instanceof Text){
				System.out.println(((Text)objDeleteInternal).getValue());
			} else if(objDeleteInternal instanceof DelText) {
				System.out.println(((DelText)objDeleteInternal).getValue());
			} else {
				JAXBElement jab = (JAXBElement) ((ArrayList) objInternal).get(j);
				Text t = (Text)jab.getValue();
				System.out.println(t.getValue());
			}
		}
	}
}