I heard that apparently the enemy icons on the main menu are supposed to act as a gallery for enemy animations, and light up once you've unlocked them. I'm pretty far into the game, and I haven't lit a single one up. Is there something I'm missing, or is that now what those icons are?
Well most monsters we can fight anytime so no need for a galary for them. For demon generals, yeah, currently no ingame way to repeat fights, but I'm sure once dev is done with all the generals there will be some way to repeart the fight, either in the dream world or by resummoning them, probably former.
I just make a save before fighting em, so can revisit the fights.
Yeah, same, but there's no telling when a save like that might become non-functional because of updates. Also, a monster gallery would be great, because then you could have a lot more flexibility. Like, you might be able to decide exactly what body part a monster was attached to, and specify what animation it should do, too. But you're right, it's definitely not that much of a necessity.