Just a note about the Fushigi no Dungeon 2 bug: That's a gameplay bug, not just a graphics bug. The score and floor numbers shown in the screenshot are nonsensical, and the Japanese text underneath (which sums up how the game ended) reads "Defeated by Shiren while carrying the Bizarre Box" which is similarly nonsense (Shiren is the default name of the player character, not an enemy)

The Fushigi no Dungeon games are notable for automatically saving to battery RAM after every action the player performs, so I'm inclined to suspect a SRAM mapping problem, although a CPU bug is also possible.