Most of the non-Chinese I know that have read Art of War don't fully understand it. Further, I've seen/heard discussions on the work go nowhere because all parties had not read the same translation. Of course, Your (Air) Mileage May Vary.
Except instruction manuals are not poetry - it's not difficult to translate them, and all of tech shares a common language (of math and engineering drawings) anyway.
The GP's point was that there exist this job called "translator" - we've figured out how to enable communication across language barriers a very, very long time ago.
Do official translations exist of these manuals? The certification that the workers in the non-US repair shops don't have is in English only. This is not a job where you want even the remotest chance of an error to exist in the manual.
I know that the prevailing opinion on this site is that all regulation is bad. However, for something like flying which is a matter of life and death regulation is literally a life saver.
Nowhere is this argument implying that regulation is bad. If those maintenance works are legal and the plane is still able to legally fly then it means that yes, somehow those non-US repair shops got the required resources to perform the necessary repairs with accordance to the standards and regulations.
Or rather no one has yet noticed whether or not the repairs are up to standard and because the US authorities can't inspect the facilities because they are abroad no one can know unless they are not up to standard and it leads to an incident.
NB I'm absolutely not implying that there is anything wrong with the maintenance. I'm implying that the US authorities would not know if there was.