Oh, here we go again...
[Woman]
Dalton probably came to this village through the
Sky Road when Sara-sama opened it.
[Man]
Jyaki-sama headed for the Sky Road to save
Sara-sama.
Elder: At the time of the great disaster,
something like a black distortion appeared......
Bosch, trying to save Jyaki-sama, who was
about to be sucked in, was also.....
Lucca: Black distortion......
A Gate......
Robo: Black distortion......
A Gate Lavos produced.
Frog: Black distortion......
A Gate......?
Ayla: Black distortion?
Thing Aylas came through?
I'm not sure I recall the line about Janus heading for the Skyway. Are you certain that line takes place after we see Dalton cart Schala away?
Firstly, just because the Elder wasn't at the Ocean Palace doesn't mean he saw it. Many Zealians survived, and some escaped the Ocean Palace. For all we know, the Elder was told about it.
The way the line is phrased suggests he witnessed the event. Furthermore, in the new Ocean Palace Incident there were no survivors to tell the tale, as all present were either killed, sent away, or remained in the Ocean Palace when Lavos destroyed Zeal. While you might have a case for this in the original incident--where Schala could have teleported herself and Queen Zeal out of the palace--you lack a case for this in the new Ocean Palace Incident. The only people to make it out couldn't have witnessed the event.
Second of all, The skybridge was opened up by Schala and Dalton, and Janus would have used it to get to the Ocean Palace.
I'm sorry? We have no proof of this.
Regardless of even if it was closed after, Janus is hiding his powers, and to save his sister he would unleash them to get to the Ocean Palace.
Uh, no. Janus is not a walking powerhouse. Sure, he has powers, and an extreme amount of pontential, but I don't see him teleporting himself to the Ocean Palace...at least not without collapsing from the sheer amount of strain on his young body. He would need substantial training before attempting such a feat, and we've no evidence he had such training.
Melchior obviously followed suit.
And this is where you are wrong. We know Melchior remains on the mainland after Dalton whisks Schala away. He never mentions going after Dalton or Schala, and obviously intended to leave that task to Crono and friends, as evidenced by his giving of the Ruby Knife to Crono. What reason would he have to chase after them if Crono and friends would stand a much better chance?
I also once again
Gaspar and Belthasar, in the second timeline, we don't know, but they could have easily have gone there too. After all, the only guru that was imprisoned was Melchior, the others left by themselves and could have come back by themselves because they too wanted the Ocean Palace to cease.
We don't know what happened to Gaspar or Belthesar. From what I recall, they disappeared or were possibly banished. As such, your comment is at best idle speculation based on a series of events that did not occur in the new timeline.
In any case, none of this makes sense. Take a look at the course of events shown in Magus' flashback...it is obvious that it is a completely different version of the event. The Mammon Machine overloads in the course of the events even though--according to your timeline--it would have already overloaded. Furthermore, Queen Zeal is suddenly outside of the Pocket Dimension again even though she was inside when Crono was killed and his friends and Magus teleported away by Schala. And right afterwards, Lavos destroys Zeal. What, he popped back inside just to banish the Gurus and Janus? I think not.
I'm sorry, but your attempt at piecing the two events together is flawed and speaks--once agian--of you not understanding how time travel in the Chrono series works.