var editor = SdlTradosStudio.Application.GetController<EditorController>();
var document = editor.ActiveDocument;

foreach (ISegmentPair seg in document.SegmentPairs)
{
	if (seg.Properties.ConfirmationLevel == ConfirmationLevel.RejectedTranslation) //überarbeitetes Segment
	{
		var target = seg.Target;
		target.AcceptVisitor(new MarkupDataVisitor());
		foreach (IAbstractMarkupData item in target.AllSubItems)
		{
			if (item.GetType().Name == "RevisionMarker")
			{
				var rev = item as IRevisionMarker;
				switch (rev.Properties.RevisionType)
				{
					case RevisionType.Delete:
						//delete action
						break;
					case RevisionType.FeedbackComment:
						//comment action
						break;
					case RevisionType.Insert:
						//insert action
						break;
				}
			}
		}
	}
}

public class MarkupDataVisitor : IMarkupDataVisitor
{
        public void VisitRevisionMarker(IRevisionMarker revisionMarker)
        {
             // Access revisions here
        }

        public void VisitSegment(ISegment segment)
        {
           VisitChildren(segment);
           // Make sure to call VisitChildren in VisitTagPair, etc. also to get all children
        }
       
        // Implement rest of interface here
        
        private void VisitChildren(IAbstractMarkupDataContainer container)
        {
            foreach (var item in container)
            {
                item.AcceptVisitor(this);
            }
        }
}