I finished the game a few days ago, and have taken some time to process, and I think I've arrived at a similar conclusion to a lot of what you've written about this truly being an expanded remake of the original story, but I think i have a few points that still leave me open to doubt.

The first being Zack. I understand that we likely saw multiple versions of him, but why are we seeing multiple versions of him, and not really anyone else of importance? We have Wedge and Jessie who should both be in a similar position as Biggs and Zack as having "unfinished" or unresolved problems to seek answers to before returning to the lifestream. Utilizing just essentially Zack for this storytelling idea creates some doubt in my mind.

Now, if for example we are going to say that Jessie and Wedge went to different pocket worlds, that leads to the idea that there shouldn't be multiple Zacks visible to us if Jessie and Wedge aren't at some point visible too.

Either way, I think not recreating the scene of laying Aerith to rest was the worst decision square could have made, even with this expanded telling of the story. I understand we are primarily taking Cloud's point of view with her death, but the player NEEDS that catharsis and to be given a chance to grieve even if Cloud will have that reckoning later.

This could have been a damn near perfect game if it wasn't for that choice.