well, I found (maybe) a bug, 2nd visit Blazing Fires of Hell, the final dungeon boss (I'm pretty sure it's name Omega Weapon in FF 6), it regen 99k + HP!!
then I give auto battle command, and after several minutes he's dead...
EDIT : damn another stuck for me, where we must find 4 switch...
there's 2 switch I can't found, and the clue left is "The switch requires a fee" "The switch requires you travel far and wide" "The switch is hidden in a spot nobody will know"
corpse switch & center switch already found.