I looked at the engine for the Japanese parsing and it looks like they are parsing Japanese in fundamentally the same way they are English and it's has been known for around 20 years that is insufficient. Japanese requires tagging be done in order to tokenize it not the reverse as is done with English.
Take a look at spaCy if you're interested in what's possible nowadays, but it's not an end user product.
Edit: it's not quite that bad they're using GoSen which stopped being used only about 10 years ago.