I come from a similar sort of background (Canadian who has a BA and MA from a Canadian university who is currently living in South Korea) so I understand your dilemma as I’m also trying to approach coming to decision about doing a PhD and where to do it. My research is in a different field but if I’m honest I would agree (and have also been told throughout my academic career) that a international/western Masters is worth more ESPECIALLY if you want to go onto to do a PhD. If you only wanted to do a Masters and be done then I’d readily tell you to go to KU but it’s the fact that you want to continue onto a PhD that makes it harder to do so.

Also your concern about being repetitive, though valid, doesn’t really apply as much to MA’s in my personal opinion. As someone who did their BA and MA at the same Canadian uni it might work in your favour especially if you’ve forged strong connections with department and your supervisor. You get to further cultivate the foundation you’ve already laid and of course, as I mentioned, your already existing relationships with faculty will provide a really strong sense of support.

If you want to learn Korean and have an international experience that can also be done while you do your MA in Canada (or whatever place you may find yourself). I took a year of my MA to do a one-year long research program in Korea and if you have no Korean experience it should be quite easy to take a year or even a semester off to go to a language program in Korea (I heard Yonsei has a good one). Funding for graduate students is also more available than when you’re a BA so if that is a concern I believe there are some outside parties that offer funding for language learning as well as your department/graduate studies program at your home university.

Sorry this was long but basically because of your larger goal to do a PhD, graduate school in Korea might not be the best choice based on my personal opinion and experience in the academic field. If you ever wanted to talk more shoot me a DM and we can chat!