I have a personal theory about how to frame these discussions of statues and memorials of flawed historical figures. Here it is:
History, particularly in the West, has been a largely (but not entirely) uninterrupted if incomplete move from the privileged few, to the privileged minority, to the privileged majority, to egalitarianism. From a king, to a king with barons, to landed white males, and so forth. Famous historical figures come overwhelmingly from the privileged groups. Pretty much the only historical figures from Western Civilization that are famous from a thousand years ago are kings, explorers, and conquerors. Most of the famous historical figures from 100 years ago are white males. This is through no flaw of the unprivileged, it is just a question of access to power. If you were a white landed male 150 years ago, you were surrounded by an unjust system. Most of the injustice was just "the way things were" and probably not even something you overtly thought about. Some of it may have been injustices that you actively worked to maintain. On rare occasions in history, some person in a privileged position actually worked actively to correct an injustice.
It is acceptable to celebrate a flawed man who worked actively to improve some aspect of an unjust system, even if he failed to address, and benefited from other elements of the unjust system into which he was born. If a white male lives in a time and place where black men are enslaved, women are treated as chattel, and homosexuals are prosecuted, and he dedicates his life to trying to end slavery, but ignores the plight of women and gays, then I think it is reasonable to celebrate his efforts to end slavery. It is also reasonable to note the less favorable aspects of his life.
So for me, the way to judge a statue of a famous but flawed historical figure, is to determine if the statue is specifically celebrating something that current moral standards find repugnant, or is it celebrating something virtuous and worthwhile (despite the other flawed positions the historical figure may have had). If city hall had a statue celebrating John MacDonald's role in residential schools, I don't think any reasonable person would support it remaining in place. If it is on the other hand celebrating his role as a founding father of Canada, then it makes sense for it to be there. Rather than remove it, I would prefer to append additional historical information, specifically addressing MacDonald's shortcomings.
This is why, IMHO, it makes perfect sense to remove Confederate leader statues in the South that were put in place for the purpose of celebrating some historical figure's act of treason while sending a (not very) subtle message of support for white privilege, but it is not appropriate to remove a statue of Thomas Jefferson. Jefferson (presumably) is being celebrated for writing the Declaration of Independence, or founding the University of Virginia. He is not specifically being celebrated for being a slave owner and raping Sally Hemmings. Those shortcomings can and should be addressed, but he still is an indisputably important historical figure who helped propel civilization forward.