I don't think the above quote should be taken lightly, and you will hear it from more or less every lawyer on this forum.
Where you are coming from is why a lot of folks take the leap, and the Canadian legal community is better for it. It just so happens that once you are actually in law school, interests change, you get a sense for what the world of law actually means (although I will caveat that by saying there is another important and transformative whole awakening that happens post-law school), and people take different paths. So, that is a key reason why you won't find any school with a particular focus on what you are planning.
This is in part a cause of the schools, and in part a cause of the person. No doubt, schools everywhere are geared towards putting lawyers into jobs. Sometimes that means a more directed focus leaning toward Big Law, sometimes it means less of a directed focus. There may be schools that offer clinics or courses that are human rights related in nature (really, all schools have this to some degree, with minor deviation), but there is certainly no school in Canada that markets itself upon its ability to put people into places like the UN. How could they? It is globally competitive.
This is all to say, that yes, absolutely choose and look for a school that will suit your interests. But, as happens to literally everyone, you'll grow into knowing that a UN-type job takes much, much more than a school, and a school ultimately becomes a zero factor.
That is not to say your interests or ambitions will drastically shift. Domestic human rights in employment and labour are real. Our Charter is real. It is just to say your interests may be applied elsewhere, in ways that a particular school's international human rights program likely won't matter much.
LSAT 163, OLSAS cGPA 3.51, B2 3.72, L2 3.76
Looking at all Queens, Western, Ottawa, Lakehead, Ryerson (maybe Osgoode if I'm feeling lucky). Average ECs, good LORs.
B2 and L2 are calculated for Queens and Western (Western takes summer courses and Queens doesn't so that's why my L2 is higher than my B2)
I think retakes are something to stress about when you take it 3 times and go from 154 to 156 to 158. A retake for a 175 is truly nothing to be worried about. I'm sure you know when comparing your stats to the median admissions that you'll get in. You are going to be completely fine.
I do think clerks at ONCA/SCC are generally from Canadian schools, but that's probably in large part due to self-selection. Students from Canadian schools are primarily the people that are the people looking for Canadian clerkships. If you do very well at HYS/Columbia/NYU I'm sure you'll be in a fine position, though that's always a big if. But it would be just as big of a chance to assume you'd do well enough to clerk at an appellate court at a Canadian School.
I would highly consider American schools if I were you, simply for the reason that you could probably go somewhere very highly ranked for very little. You could swing a very significant scholarship at many schools with those stats.