This is an ongoing issue with abuse.

https://www.yamahasynth.com/ask-a-question/why-are-japanese-or-chinese-posts-appearing-in-this-forum
https://www.yamahasynth.com/ask-a-question/japanese-text
https://www.yamahasynth.com/ask-a-question/japanese
https://www.yamahasynth.com/ask-a-question/unusable-site

In response, we now have a spam filter that more easily marks my own posts as spam. So I know at least one tangible change has been made and probably more I am not aware of. Still, even with the attempts to prevent the spam, the spam still gets through. I would suggest patience when you see this as eventually the moderators clear the spam and things go back to normal for a while.