im not sure

it sounds like a glitch if you can walk through the characters but not talk to them because once you split you can't see the other characters at that point again you have to go down to where you fight Jenova and Sephiroth

so..........i think its a glitch and youre stuck. sorry

if you like, ill tell you an awesome place to train (heard from my brothers friend, he plays ff)

it takes longer than in the northern crater or the sunken airship but you barely take any damage, you can kill the opponents much quicker and you get a decent amount of exp, ap and gil