Well if you don't care about US "validation" you wouldn't use Billboard as a benchmark to begin with, because at the end of the day Billboard is an American company and their main domestic charts (Hot 100 & Billboard 200) are considered the prestigious ones. Basically only Kpop fans ever cared about their global charts, and in reality there's no single music chart that will actually tell you what the most popular songs or albums in the entire world are.
No idea why people use west when they think USA.
Companies do want to have success in the west/USA. Bts and it's members charted on hot 100, bp and its members too, newjeans, le sserafim, stray kids charted too. Illit with magnetic. Is there anyone else? Come on Yama-Chan chart king, help me . So it's not impossible but it's hard.

interesting. I was not aware that Katseye have never charted on AM.