let me get it straight to you
neural networks for other game genres like platformers work because the way to success in those games can be rather complicated and not very straightforward
in bullet hells, especially in touhou, all the bot has to do is not die
hence, all you have to do is copy PoDD/PoFV's AI style and have it dodge anything around it reactively and it can clear 99% of patterns, and if it gets hit, just get it to deathbomb on the first frame
there's not much point to making a bot for these games
as for danmakufu, good luck because it's certainly no easy feat to even have a second player, let alone AI that doesn't fail horribly