AFAIK, they don't have a dedicated local board but just a dedicated thread in other languages. So everything they post has to be in that thread alone which is why it is impossible to say which is an off-topic comment also I remember the moderator's comments regarding such copy/paste in other language boards, mods don't consider them as off-topic, and will not delete.
Yeah I can imagine that its harder (or impossibke) to get rid of off topic in those cases, but shitposts can still be removed.
I have warned those members doing these things, but I don't know if it would work.
If you think that they are merit fishing shitposters, you can always leave them neutral feedback so external merit sources know who they are dealing with. With some people you just have to get rough for them to understand what's right and wrong.