Intersting. The dejavu means the save point has been used, but the save point only activates when the owner dies, right? So this means that Junko died here, maybe even more than once. But who killed her? Not Elis because she's fighting Wendy. Did Hinako manage to kill her despite having no cheat ability?
According to Carla, Junko used the save point three times prior to Elis's fight with Wendy. In other words, we only see the fourth version of Hinako's reunion with her ex, and things probably played out differently during Junko's other three (failed) assassination attempts. It's therefore possible that Elis
did kill Junko during one or more of them, but there's no way for us to know.
Junko trafficked another girl at their school into a prostitution ring. Other girl murder-suicides Junko... Hinako tries to save them but dies also (she seems to have lost her arm in the other world but also before being Isekai'd? *
It's not at all clear that Hinako dies in this chapter's version of Junko's meeting with train-kun.
[SEE @1idd0kun's REPLY BELOW] EDIT TO ADD: What we see in this chapter is not the train accident in which Hinako dies.
During the collision, Hinako is struck by Munakata's severed head and knocked unconscious. When she recovers, she's lying on the platform face-to-face with the ghastly thing, though it takes her a few seconds to figure out what she's looking at (see pages 21-23).
It seems likely that Hinako also had her arm torn off by the train,
and it's possible that she survived only for a moment or two. Then again, but the unseen emergency responders on page 23 were probably talking about her when they said "There's one still alive over here," suggesting imminent rescue. I mean, it's a great chapter, but it raises far more questions than it answers...
* I removed your spoiler tags because it's appropriate to discuss the events of chapter eight itt.