Ah, going by the initial thing of "what you struggled with" it felt like these went here.
I poked at the Kari thing a bit further, and I managed to trigger the mall meeting, but I loaded the save a few more times to doublecheck some stuff. She doesn't specify "dusk" in the dialogue, just "after class". Heading back home, the diary (which I had checked a few times before making my post) is a little more clear at saying "before dark", but it seems rather easy to miss the specific period of "dusk", as at least a couple of my attempts managed to clear the entire dusk period before I could reach the mall. (Namely, one where I headed home, swapped outfits, went to the mall at "afternoon", went back to the house and ended up at "dusk", but going back to the mall ended up at "evening"; somehow used up all the dusk time in coming back from the mall and going to it again.)
As for the mushroom puzzle, I had spent some time with the pages trying to identify the shrooms before I finally managed to stumble on getting the book... about all I could figure appearance-wise was that "one of the three important shrooms that look the same glows at night" and the visual link to reality for another type. And it felt in that one of my runs at it, I collected two glowing ones and they had different effects upon consumption, hence the sense of RNG I had.
I'll admit that if one of them had an audio cue like the research pages imply, I may not have heard it due to outside audio at the time.
I still don't know how I got all the trees to be colorful on one of my attempts.
The bars I had some hints for, having played some very early versions of this long ago, but I was misremembering some of the differences between Mind and Will. Good to know on the Cohesion and Dissonance, and I can't believe I somehow never registered the Hunger and Thirst indicators.
There's definitely lots of stumbling in the dark, but am still gonna keep poking at it, heh.