I had filmed a sample clip of me playing Krion Conquest as visual evidence that the game indeed does work. I might do a similar visual clip with Dragon Warrior II, which is another game disputed to not work on the FC Twin (but it does – on my end at least).
It can be argued that it might have to do with the individual cartridges, similar to certain . I’ll give it a go on one of my lesser NES clones to see if it works there, but for the most part (on my end), it works fine.
Maybe it’s a glitch later in the game. I’ll have to find that out by playing further.