I published a technical book in the late 90s and the publisher (Pearson) opted to have it translated into a number of other (non-English) languages. I was never told anything about the translations. My assumption was that they used some sort of "contract translation people/service" and just "crank them out". My guess is they aren't that focused on quality. When my book was first published, technical books were much more profitable, but since then publishers have really struggled. The publisher I worked with was fantastic at the time, but since then has repeatedly stated they just want to "get books out there" regardless of the quality. And, I think the market was already tanking by the time my book was translated, so I'm pretty sure quality wasn't a priority for them. They sent me an after-the-fact sample copy of 2-3 of the languages it was translated into, but it was a total surprise to me and I never received any information about the process or that it was happening. In fact, it was so hands off that I have no idea if they translated it into more languages and never sent me a copy.

Another factor why the authors the OP contacted may not care could be that the royalty rates were dramatically lower for International sales -- at least that was the case for my book -- I essentially made nothing. I'm not saying people write books only for profit, but the combination of "not even knowing they were translated" with "zero profit motive" makes a potent combination. :-)

That being said, I don't believe anyone every contacted me with errata on a translated edition... I guess I should consider myself lucky. :-)