You pretty much had me until the last question. Basically from my own observation, would LCK have a harder time? I would genuinely answer yes. It would very likely not be some whitewash "all Korean teams are overlords," "low Korean would place high in X" scenario either.
Now idk about you or anyone else, but I found the mid to lower Korean teams making quite a few bone headed individual plays or actions this summer at the least. Only speaking on terms of the major regions, frankly if the team fighting of the likes of JAG, ROX, MVP, and/or AFS should be something of a force to be reckoned with, their chance of a solo or duo blunder is most certainly something that isn't unlikely to me. That puts their ceilings not as high as I would like to say to be honest. Compare that to other 5-8 teams (4-6 for LMS). I would nearly omit AFS on this observation but I do feel that the top potential in those LCK teams would not really eclipse the likes of the collective potential from the other regions.