They were literal ghosts walking on a beach and they didn't appear in yhe sequel despite being powerful demigod beaters following the events of Chrono Trigger.
.... yeah.... they're dead. And even if they weren't dead, Dalton undoing the world order is still character and immersion breaking.
I was having these same arguments on GameFAQS 15 years ago. There was a Kato interview floating around where he laid out his Chrono Break idea that had Kid partnering with the CT gang, but apparently I can't easily find that right now so I'll try and do it the hard way.
One of the more subtle themes of the Chrono series is that the planet is a sentient being, nudging our heroes to stop Lavos from the destruction it recognizes will happen.
From the Fiona's Forest sidequest.
Robo: I realized something during these past four hundred years. I believe we
may have been incorrect in our assumption that Lavos was responsible for
the creation of the Gates.
Marle: What do you mean?
Robo: It is not a certainty, but I have come to believe it possible that some
entity wished for us to witness these events. Perhaps it wanted us to see
all of these various ages. Alternately, it may have wished to see them
for itself. It seems almost as though it was reflecting on the days of
its past.
Ayla: Ayla know. Person die, see life pass by. Elder say!
Frog: Before death claims a man, he is made to bear witness a second time to
those memories engraved most deeply upon his heart. There may be fond
memories among them, yes. But often as not, the ones which grieve us are
the most profound.
Robo: Knowing the end is approaching likely reactivates dormant feelings of
regret, and desire to return to moments in the past.
Marle: Do you suppose that will happen when our time comes?
Lucca: Probably... Who knows?
Marle: Is there a point in time you'd want to return to, Lucca?
Lucca: No, not...not really.
Marle: I'm sorry, I probably shouldn't have asked.
Lucca: No, it's okay. It's just something I don't like to think about too much.
Frog: But even if Lavos did not open the Gates, his fate is clearly bound to
that of the one who did. Lavos has played a role in every age we've seen.
Magus: Who do you think it is?
Robo: It is unknown to me whose memories these are. It is likely an entity
greater than any of us. Perhaps we will not know until our journey has
come to an end. Shall we turn in for the night?
It's more plain spelled out at the end of the game.
Lucca: Do you remember that talk we had?
Marle: You mean about whether our lives flash by before we die?
Lucca: Yeah. I get the feeling that...entity is finally at rest, too.
Marle: Yes, I feel it, too.
Now comes Chrono Cross. From the introductory text in the manual.
The dream our planet once had
Defeated the darkness
And brought forth a brighter future.
However, this was also the dawn of
A new nightmare...
The final battle over the legendary treasure,
"The Frozen Flame"...
A battle between dragons, humans, and fate
That will surpass even space and time...
Is about to begin...
Our planet's dream
Has not yet ended
Now here's what we know about the "ghosts" in Chrono Cross.
- They're children, younger than they even were in CT despite the game taking place 20 years later
- Their knowledge and attitudes are vastly different than their known characteristics
- Their words are intended to push the Cross cast to destroy the evil threatening the planet
- Belthasar is alive in Chrono Cross. We know he can create illusions. He has the power to appear as a ghost
My interpretation is that the Belthasar is manifesting these illusions as a proxy for the planets desires. We never get confirmations or even hints of Crono or Marle being in danger or dead aside from these manifestations. Simply taking these illusionss as proof that they're dead is overly simplistic in a very complicated story.
