Not really. He made the comparison of two tapestries looked at from afar, looking much alike, while the closer you got the more you'd see the details are completely different. So I wouldn't say it's "minor" details. The Ages are probably far more different than people think, or rather a lot more belong with the details than we might think, otherwise it totally defeats the whole theme of the ending that makes balance be about the ability for everyone in the Pattern to make choices.

Many tend to forget that ta'veren and ta'veren pullings are the exception, not the norm, and RJ was very keen to say the Wheel/Pattern didn't remove free will.. it's mostly for Rand it was all about making one fundamental choice, and having no option but being brought on the path where he would have to make that choice for everyone in Creation, after being shown "all the secrets".. then he get a reward "free life" to do as he pleases, and he's even allowed ton make little changes in reality based on his understanding of how Creation works. Now for him it's all about refraining from interfering anymore, the Creator's challenge, but with his spiritual epiphany outside the Pattern, that's a challenge he should live up to.

Shai'tan had hundreds of thousands Chosen in the AOL, and in the top ranks there was an heavy rotation. There's little reason to believe all the thirteen are necessarily "key ones" and not "details".

He also said things evolved with the turnings.

As for the DO having the ability to remove souls from the Pattern, it very likely exists. Wolves who die in TAR don't return.

It's solidly implied that if mindtraps for example are destroyed, it destroys the very soul of a person. Sammael is another soul that most likely got destroyed forever since it's heavily implied Mashadar/Machin Shin "dissolved" or absorbed souls, and it becomes a dark energy/power opposite yet equal to the DO's, that by the rules of the cosmology can't co-exist with the DO. It means the Cleansing likely destroyed all the souls captured by Mashadar.

Brandon didn't go much into the DO's powers over the dead (even largely forgot to involve the ghosts and apparitions after the first few chapters), so it's hard to tell. But there's not much to suggest the souls Shai'tan chose to grab aren't outside the Pattern with him, since he wasn't technically inside.

There are also souls that won't be reborn now that Shadowspawn will go extinct, since RJ said that the souls that lived a life as Shadowspawn are forever tainted and can only be reborn as Shadowspawn.

It's also implied at the end of the series the DO remains an evil influence, to allow that ethical choice within the Pattern. He's just prevented from interfering directly until the Bore is drilled again. Time doesn't exist, so in theory it's perfectly possible there are souls in Shai'tan's possession that he will be able to transmigrate only once the Bore gets opened again.

We also know the Grey Men's souls were in Shai'tan's control, and likely outside the Pattern.

Moridin was able to step outside the Pattern, but probably only because the Bore existed.

The Balefire thing is largely a misconception, since some of the characters believe it might destroy their soul forever, when in fact it burns the life threads in the Pattern and does nothing to a soul. RJ explained threads and souls are related concepts but separate things.

I tend to agree it's unlikely any of the Chosen's soul is currently in Shai'tan's possession. They all died while He was focused on Rand. He only has small windows of opportunity to reach and capture souls. Lanfear would be the one he has the best odds to have catched as she died in "slow time", but she didn't exactly died at a moment when Shai'tan wasn't busy trying to cut Moridin from the True Power...