it seems "boss3_clear" was not defined as a global variable like the others in the dev's battle system. A simple enough fix I suppose, not that it mattered in the end cause there's no more content after that (besides unlocking 2 massage2 events). I'd consider it common courtesy to let the player know when reaching end of content. A simple "And that's all folks. See ya next update!" would've been enough.
There's potential here, but would certainly appreciate more content outside the dungeon, more interactions with party members and such. Even a nod, or a "wow, you got stronger!", just a freakin acknowledgment or something. Unless I missed it due to another bug/s. Endless grinding in the dungeon with minimum payoff is certainly not my idea of fun.
Wish the dev is not discouraged by the criticism and takes it to heart. Like I said, there's real potential here if it's polished a little more.