@Salfaro In all fairness, she doesn't know their old party member anyway so seeing his name wouldn't necessarily cause any immediate suspicions. It's entirely possible she may have looked at him and merely not commented on him. The way they describe being either "good" or "evil" seems to imply that it might not even be outside the realm of possibility that they wouldn't be entirely surprised if he showed up as "good" too.
@sirflimflam She kinda does, though. She was the one who scouted him out and recommended that the hero party pick him up, so even if she doesn't know his name or face for whatever reason, she knows that he was a powerful necromancer child, which is probably an uncommon thing. Knowing that much, if she looked at him and saw that his race was human and put that together with him being child size and in control of a new graveyard dungeon, she would probably be really suspicious at the least. And then all that would be needed to completely spill the beans would be for her to mention that + call him by name (shown in the spectacle) in front of the hero.
@Salfaro Either she already know but didn't say due to them being asses or She did but it is ????? (to visualize in old game when you analyse the boss it gives ???? ) due to high level or protection or she did not bother since bosses stats is ????? so she assume it would be pointless or she forgot due to her teammates being asses.
Maybe it's a game over [bad end] scene the hero gets whenever he turns evil? No matter where he was, his equipment abandons him and the demon lord appears to chastise him?
Israfilis could probably turn the ex-hero into a plague carrier and send him back to the humans. The best part is that even if the dude knew he was carrying a plague, he would still go back, instead of isolating himself. That's his personality.