I've known so many researchers who apologize every other sentence because they say they've only read English and I would never had known otherwise.
Which is to say - it'd be wierd to say "well I don't know English and I don't know anybody who does oh well". But, anyway, the papers were published on aeXive in...
Plenty of people would learn Latin to consume some content, but doesn't mean they are proficient in it itself, would be another example.
Having said that, I think that in the research field that merely ends up with "very confusingly written papers with mistakes large enough to hide process errors" more than "cannot communicate any info in English". But there are plenty of people who get their doctorate and their only English-language output is their final papers in themselves.
The paper is just a guide. Who would replicate likely needs to contact the authors to understand the implicit details of the recipe. That is process knowledge. There's a good reason world-leading lithography happens in that region. With luck, researchers and engineers will be able to refine and industrialize the process these coming years.
Japanese and Korean professionals speak English. There will be one researcher for whom explaining the language is a minor dalliance.
I work in a very minor polymer materials field. There are two Japanese researchers who cheerfully banter. If somebody had hidden some transformative work behind their language, even as a student, they would have talked about it straightaway, if only for the conversation and a bit of competitive intellectual football. Can the foolish American grad student reason around it? Let's see!
The twitch channel was packed with interested Koreans. If there had been the tiniest bit of confusion there would have been 200 translations from which to utilize the Translation Of The Crowd.
Of course the Japanese scientists you've met speak English. People who don't speak English well enough are not generally going to participate in events or situations where they would need to rely on English-language speaking skills. That someone apologies for their bad English is, of course, irrelevant; if it were truly bad you wouldn't have encountered them. Likewise, Japan has many international science programs, forums, and conferences; and they'll be filled with proficient Japanese English speakers, but Japan is a huge nation so it says little necessarily about broader patterns.
I don't doubt that a majority of professional research scientists in Japan have some proficiency in English. Especially the top scientists; even in Japan "impact" would undoubtedly be heavily biased toward publication in prestigious international journals. But there's plenty of literature on the internet that describes the relatively poor English-language proficiency (especially conversationally or with verbiage outside that in their technical field) and poor English-speaking research community integration of the broader Japanese scientific establishment. See, e.g., "Japanese materials scientists' experiences with English for research publication purposes".
I first encountered this cultural dynamic when researching the tilting of the Millennium Tower. While friction piles weren't first used in Japan, Japan was where friction piles were first heavily researched and employed for large buildings, including skyscrapers. People kept saying friction piles were idiotic in earthquake-prone, sandy soils, but that's precisely the environment where they were first researched and from whence the global engineering community's confidence sprouted. However, AFAICT much of that research was published in Japanese, even through the late 20th century and (IIRC) even early 21st century. Was that Nobel-worthy science? No, but it was very useful applied science; and applied science which was highly consequential to global engineering and architecture, notwithstanding that much of the substance of it existed on the other side of a Japanese language barrier.
[1] See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8024886/
[2] E.g. many of the publications by the The Japan Institute of Metals and Materials are only or predominately in Japanese. Some domestic publications require require summaries and tables in English but permit the text to be in Japanese.
Friction pilings have been in use in NL for 100's of years.
As someone who sucks at languages, I can appreciate that learning new languages does not come easy to everybody, or even to most people, especially in older age. If it seems like all reputable scientists have some English proficiency, that's a selection effect--within the English-speaking world in particular you're not going to bump into or even hear much about those who cannot speak or write English. AFAIU there's a substantial amount of high quality research in, e.g., Japan that is invisible to non-Japanese speakers. Japan's scientific establishment long predates English as a global language, unlike China; and unlike many European countries but similar to the United States there was never a widespread norm of learning foreign languages even among the professional classes, AFAIU. Though Korea is a younger industrialized country, I wouldn't take for granted that the principal discoverers have any English proficiency, especially considering that they would be late middle-age or older if they were working in the lab in 1999.