Yeah, Tifa and Aerith's friendship didn't get a huge focus bc Nojima wrote it all down in TOTP and only a few people have read it which is a bummer bc I would have like it if they incorporate more stuff from TOTP into rebirth, big disappointment on my part, but oh well, can't do anything about it now haha
About Aerith appearing to fight side by side Cloud, I can imagine they would be doing that bc this is her game and a callback to AC/C when they stood back to back. Kinda like Zack and Cloud's fight against Sephiroth
But when thinking of Aerith doing that to Tifa and then what? She never shows up again for Tifa? In on the way to a smile, while she was mourning for Aerith at the FC why didn't she show up there to comfort her, why only let Tifa felt her presence? And her talking? Also, in AC/C too, Aerith was there, she could pull Tifa into the white void and have a chat with her but all Tifa felt again was her presence.
It's not that I don't like it. I'm in between haha and I said that could maybe be a possibility and if the devs do that do that it will cool to see. I just feel that if that happens and then Aerith never shows up again in front of Tifa even if she shows up in front of Cloud, it will be disappointing, maybe not to the players, but I'm sure will be unless they remake AC/C and do have Aerith show up I'm front of Tifa one last time
Sorry for the long response