And also, how is this event taught outside of China? Growing up in Canada, I've had nary a mention of this event during my public schooling. Is this mentioned in British and French history curricula? How is this taught in higher education?
What was the contemporary view of the looting?
u/enclavedmicrostate has written about the sacking of the Old Summer Palace in a post which notes some contemporary views of the event.
Century of Humiliation
The ‘Century of humiliation’ is a fairly recent historiographical construction. Rather than reflect how those in the 19th century viewed things, it has more to do with how people in the twentieth century related the late Qing to their own ideology. The concept still appears in secondary school curriculum outside of China, and is still basically the paradigm of official state history within mainland China. But outside of China, most of the relevant scholarship uses much more nuanced frameworks for looking at the late Qing.
The same author discusses the ‘Century of Humiliation’ in posts Here, Here, and Here
How is it taught outside of China?
These sorts of questions tend to not get answers on this subreddit. Curriculum is often very diverse within countries (as in Canada where it tends to be set at the provincial level but also differ between school districts and teachers). As for how it is taught within higher education, the earlier posts on the historiography of the ‘Century of Humiliation’ discuss that in some detail.