Hey! First of all, thank you for the detailed post. I'll take care of the reported bugs as soon as I can!
Composition-based conversations are coming, the ones added in v015 were more or less a proof of concept for me.
There's only one book as of v015.
I'll update the cheat post with the new item IDs as soon as I can! Gabriel's portrait missing is a bug.
I found out the reason for jitteriness and am fixing it in v016. It only affects certain devices but my fix should work for everything.