Thanks for the TL. Im just curious what is tsuno shimeji? I tried googling it but cant find anything unlike kaentake which is horrifically poisonous lol.
Looking at a couple Japanese pages it seems like the main idea is that although you can find it in other countries it was only discovered in Japan in 1989 and it's rarely found there so no one's confirmed whether it's poisonous or not and guidebooks will tell you to err on the side of caution and not eat it. So yeah, an "inedible" mushroom.
I think this just reinforces that the poisonous vs. edible mushroom divide is based on human knowledge of mushroom properties rather than the properties themselves.
If humans don't know if you're poisonous or if they put you in the wrong category that matters way more than if you're actually poisonous or edible.