Yikes! Does Amazon allow you to change your name after you've put up a book? You may want to add a middle initial or middle name.
People who choose pseudonyms have an ethical responsibility to make sure that name isn't already taken. Especially if they're going to write something that is controversial. But getting them to do it is hard. It's also possible they've been using that pen name for years but you wouldn't have had any reason to know that until you published your own book and then they released some work on the same platform.
Edited to add:
Question: Is the "ethical responsibility piece" common knowledge? Or codified?
I would call it common sense. People do have a legal responsibility to research other business names before naming their own (and part of that involves businesses registering their fictitious business names too, something that is only required in some places, or if you want to accept checks made out to that business name).
And I looked it up...turns out a pen name is a fictitious business name. It kind of has to be, since that's how you're paid. But you register locally. In my case (for my non-writing business), I registered with my county. In some places it's with the state. I don't know the laws for the (unnamed) foreign country the person you're talking about.
So, I'd say, yes, there is a responsibility to check for the name before taking it as a pen name, but the fact that this is happening over two countries and two languages makes unlikely to happen and near impossible to enforce. Unless you can prove they did it on purpose to sully your name as a public figure.
