Interesting. I'd always assumed that the vast majority of spamming/shitposting occurred in the English sections because most signature campaigns only pay for posts in English--and I don't visit any of the local boards so I'd have no way of knowing about any spam problems there.
I don't have data to support this but I'm afraid that spams shifted to local boards for a few reasons
first, there will be less people checking and reporting because language barrier
second, it will easier to post in their own native languages and get merit from their own countrymen
(nationalism) third, less likely to get caught and banned by conducting plagiarism-by-translate in local boards