There's probably a lot of reasons why non English programmers stick with English keywords, beyond just language/tooling support. Learning new keywords is already part of learning a programming language, and much of the documentation and resources available for languages and libraries are only in English. ASCII-only strings are still ubiquitous in software, like URLs and usernames. And in international teams, English is the go-to lingua franca.
Could this change with LLMs? Maybe, but most code in its training data is in English, so LLMs likely work most effectively in English.
One distinction though: Han uses actual Korean words, not transliterations. 함수 means "function" in Korean, 만약 means "if" — they're real words Korean speakers already know.
Your example uses transliterations like 펀크 and 아래이 which would look odd to a Korean reader. That difference matters for readability.
It never really took off. I think because computers already require users to read and type Latin letters in lots of other situations, and it's not that hard to learn what a few keywords mean, so you might as well stick with the English keywords everyone else is using.
Technical people already have to make concessions to deal with ascii chars and English in computing by the time they use a terminal, so the upside of changing any one thing kinda peters out.
Changing syntax doesn't change the surrounding world. Unless you plan to translate half of pip and npm you mostly end up with a teaching language or a local curiosity.
I hear that information processing speed is nearly the same across all languages though regardless of density, so in terms of processing speed, may not make much difference.