I beat the mod! It took 90 minutes for Yuri to punch the final boss with Eternal Key and the weakest weapon, lol.
Overall, good work, although I think changing the order/difficulty of the sidequests would be good. Neam Ruins was probably the most annoying one, since it had the hardest enemies, hardest navigation, long times away from a save point (I played on a real PS2, so no save states), and the games forces you to use two characters that may be severely under leveled. In my playthough, I think was naturally around 67 to 69 on my mains and around 54 on my offs by the time I finished the other sidequest dungeons, so there was a lot of grinding to do. Alternatively, making it easy to grind just before Neam Ruins would also be fine.
Additionally, if you use Rage + Energy Charge + Mind's Eye + Third Key on technical ring (Lucia's 100% crit is actually unnecessary), you oneshot bosses, so maybe the post-game bosses need more health.