Any day of the week all of the big tech companies will have dozens of overseas engineers in the US attending meetings, and gasp working on-site (writing code, etc). They all have either tourist visas or visa waivers.
And it's the same thing when the US engineers visit the remote sites in other countries.
Regardless of what the letter of the law is, this has long been the practice, because it's the only workable solution and is clearly within the spirit of the law.
In this case LG was fitting out a new batter factory. That is a very complex setup with highly specialized machines. The ONLY way that was ever going to happen was with LG specialists coming over to do the setup and get the line working. And it's almost certain that getting "correct" visas for all these people would have been practically impossible, and has not been the actual practice for many decades.