I’m afraid that is a pattern for Camilla. Originally, she was not expected to go to Australia with Charles, but I guess the courtiers, in their wisdom, must have thought that her not going would be interpreted as a snub to the Commonwealth and insisted that she attended the opening ceremony, which was actually worse as she looked bored and detached.
The hard fact is that Camilla is already 70. She is no longer a young, energetic woman and long tours like that may not be particularly pleasant for her. That is why I think those kind of events are better left for William and Kate, who still have the vitality to do it and seem to be a hit wherever they go. Of course, right now, Kate is on maternity leave and cannot travel , and Charles cares deeply about his future position in the Commonwealth , which he, justifiably so, sees as uncertain.