The case involves headnotes, not just key numbers. Your links provide examples of such headnotes, which make it very clear that a lot of human creativity and judgment is involved in authoring them - they're not a matter of purely factual information, such as a phonebook. Thus, the headnotes are copywritten, and translating them to a different language doesn't negate that copyright. This looks like a slam dunk case, but it has very little to do with AI training as such - the AI was only used to create a kind of rough indexing over the translated text.
If this was only about key numbers, it might have gone the other way because the fact-like element there is considerably greater.
Case law is public domain. You can publish digitized copies of Westlaw books with the headnotes, keys, and a couple of other property bits redacted. Any of their proprietary elements though, definitely including the key cites, are clearly a no-go. The headnotes not only require creativity and expertise to make, many lawyers consider them indispensable (though many other lawyers apparently throw shade at lawyers that rely on them.) And since most of the rest of the book is public domain, it’s one of the biggest, if not the biggest selling point for their texts. They famously vigorously defend their copyrights— the defendant surely knew what they were signing up for when they started doing this.
If this was only about key numbers, it might have gone the other way because the fact-like element there is considerably greater.