I'm terribly sorry for the late reply, I wasn't able to apply the fix you recommended because I enjoy visual novel more when I'm playing it on mobile. I've been playing the game on Joiplay and it works.
As for the fix I found that if you use the default name Edward (Basically just don't make a custom name for your character) the game proceed normally.
I found this by repeatedly starting a new game, and based on your previous replies on the comments below, you said the bug was "random". But for me (who always had a custom name for my VN characters) the bug occurred 100% of the time.
So I tried just now going by the default name and the mushroom event triggered.
I just wish I had found this sooner lmao. I'm excited for the 0.4 update btw