Instead of giving up on your community, why not reporting that spam instead?
Another thing, if people are spamming nonsense copy/paste news and are getting merit for it, you may wanna warn those meriting them that they are not doing any favor to your local thread as that will only make them spam even more of the same stuff.
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.
But what the members can do is ignore those users and not merit them so over the period they will vanish.