“Japanese people are too kind,” lol. People from any country are pretty much the same; there’s no such thing as Japanese people being especially kind. I don’t know whether you’ve actually come to Japan, but what you’re calling kindness is really just a form of Japanese basic etiquette and manners, which you’ve mistaken for kindness. In fact, that’s just your imagination—call it prejudice, delusion, or memory-glossing. Sorry, I don’t know how to get this across in English. But I think you can get what I’m trying to say.
So it’s not that Japanese people are too kind to give negative feedback to the artist. The reality is that, generally speaking — and I mean generally — Japanese people won’t formally make negative comments just because they dislike the content of a work. Whether someone likes something or not is entirely a matter of personal taste, and in recent years there’s also been a strong emphasis on diversity.
However, if there are actual quality problems, then Japanese people will definitely give negative feedback, they may even spread negative comments widely on social media or DM it directly to the artist, just like people in other countries.
(Sorry for my bad English. I’m using a translator.)