The only thing that changes by talking to monsters is that you don't hear what they have to say, and you get experience and items for winning the battles. The thing with the Speak Monster skill was an accident; I copy/pasted the conditional branches for the other spells and changed them as needed, and it's extremely likely I missed one. You CAN get the missing notes, but it requires fighting to get them. Taking the pacifist route gets you more lore and memories, but you forfeit some of the notes from the bosses as a result. I do plan on continuing to polish the game. There's a LOT I didn't put in that I WANTED, but I also wanted to really keep this game to as close to an hour as I could.
Thank you so much for playing. I'm glad you enjoyed it. Some things I wanted to purposely leave confusing, but a lot of the confusion was my panicked patchwork job in the last week.
And yes, not doing the Earth Cavern means you do miss some of the main story stuff. But I thought it might be more interesting to have the main story be optional.