I didn't realise that HM's trip to Canada wasn't well received. I always believed that the monarchy was most welcome in Canada, if only because it prevents Canada's being subsumed into the US. This last, of course, is not meant as any aspersion against America.
About Charles' standing in Australia. Well, he was rather popular, I believe, until the breakdown of his marriage with Diana. Without going into the wrongs and rights of all that past history, it's my opinion that his marriage to Camilla has made him even more unacceptable. Whether that's fair or not is another issue.
And then there's the issue of Lady Tryon, an Australian, and another alleged long-term mistress of Charles'. The animosity between her and Camilla over many years, when the prince, reportedly, divided his favours between the two of them, rankles with those who knew her, many of whom were/are influential, particularly as her death was such an appalling one.
In all honesty, republicanism has been gaining strength in Australia for decades. Prince Charles himself sounded most aggrieved when he offered himself as Governor General and was told 'no thanks'.
HM was born to Empire and embraced the notion of the Commonwealth with gusto. She is deeply admired in Australia, good woman that she is, and it's felt that her like will not be seen again. However, given the popularity of William when he visited, all is not yet lost. Interestingly, it seems to me that he's admired as his mother's son, but not his father's!
In diplomatic circles, I've read in the past, Camilla did not show to advantage while in Uganda. First, she was 'over-loaded' with millions of pounds of jewels (even I thought that she wore too many and too much) with a heavy tiara which doesn't flatter her, in my opinion, and that huge diamond necklace. Observers complained that she was insensitive to the economic stresses and abject poverty around her, and those countries which many CHOGM leaders represented, pointing out that HM was much more appropriately and modestly adorned.
There was also another, significant, motive to the Duchess's new majestic style, it was suggested. The Royal couple's four-day trip to Uganda was officially classed as an independent visit but it was seen by many as effectively a "job application" by Charles to succeed the Queen as head of the Commonwealth. It coincided with the Commonwealth Heads of Government meeting and is the first time the Prince has visited the same country as his mother at the same time for more than three decades.
Australians are often a puzzle to me. Whereas we readily embrace Mary as Crown Princess of Denmark, commoner that she once was, we object to Camilla and apparently resent her. Very odd.