Earlier quoted context omitted.
"Of course data is copied during training" is copying. As far as I know, the law is consistent that temporary copies are also covered by the copyright act, and that's how some analogous cases were resolved.
Temporary copies are in the scope of copyright law, yes. But also, you are allowed to make them. Or reading a book via a computer would be illegal.
Not of physical media. You're allowed to make archival copies of digital media.
> Or reading a book via a computer would be illegal
No you purchased a license (or your library did, in the case of e-borrowing) to read the book on a computer. That makes it legal.