I think the genius of the pink blood is that yes, people who have played Danganronpa (or are familiar) totally fall for it, but also if you're totally unfamiliar, no one really reacts appropriately (as in, like you would in the real world) so I think you'd easily be duped in the same way. It's really only if you recognize that Yuma has red blood, but you could easily justify that it's red in the Labyrinth... for whatever reason.

I think you nailed why I also thought Yuma/Kurumi doesn't work that well. They are cute enough but it's not the same as Yuma/pretty much anyone else. But maybe his personality is different now and he's one of the ridiculous weirdos haha.