Currently these are the only giant boss fights in the game.
As for the soundtrack, 95% of it are tracks that I bought to use from the rpg maker store, the exception currently is Viscous boss theme, that one is original <3
Wait a second, am I misunderstanding? is "Viscous boss theme" literally just the name of the song and is used in the Goddess Dahlia boss fight (it might also be used in other fights, but I specifically remember it from this one due to it being the first fight I actually lost)? Because I have NEVER played any RPG that has used that banger of a song before.