You're not applying logic, though. You're applying an assumption that would fit your view.

That's quite ridiculous. The Aes Sedai standard for entry is a product of this Age. RJ said 62.5% of "the" bell curve would be accepted. "The" Bell curve is the same distribution that spans both Ages, the only thing that changed is the number of channelers that were in the population. There's zero evidence that only the stronger channelers got weeded out. RJ explicitly said that the reduction in number was due to the male channelers being removed from the gene pool. He also said this reduced the number of sparkers. He also said there is no correlation between having the spark and strength in the One Power. There is therefore no mechanism by which culling male channelers would lopsidedly only remove stronger channelers.

No such thing. You're making the fatal error of assuming strength level= actual strength. If Lanfear is strength 100, it is perfectly possible that the upper levels are separated by, say, 5 strength units. But the Aes Sedai range of strengths has more resolution, ie. more levels, since that's where it mattered.

For example, if Mesaana is 89, Nynaeve 90 and Semirhage 91, they'd all be lumped into the level which corresponds to a strength of 90, because such minor strength differences don't matter to Foresaken, and an Aes Sedai like Nynaeve is so rare that a point here and there is going to make no change to how much a weaker AS defers to her (which was the primary purpose of this scale anyway).

On the other hand, Siuan may be 60, and Leanne 58, but these are counted as different levels, since for Aes Sedai, such small differences can have major impacts on their interaction.

Thus, the channelers at the "+" level aren't following a different scale. The resolution of the scale is different.

The problem is, as usual, that you devalue Aes Sedai strength too much. You think it is plumb impossible for Elaida to be more than 50% Lanfear's strength. I don't. I think it is perfectly reasonable that Elaida is 60-65% of Lanfear's strength. On the other hand, I'd put the level that is "just strong enough to Travel" as being at 45% of Lanfear's strength. The majority of the named Aes Sedai fall in this strength range.

Now consider these statements from Cadsuane:
From Kerene, it's a sharp drop to the next five. Five once this child and the Sanche girl reach their potential.

No one has come to the Tower in a thousand years who could match me. No one to match Meilyn or Kerene in almost six hundred. A thousand years ago, there would have been fifty sisters or more who stood higher than this child. In another hundred years, though, she'll stand in the first rank.

Don't you see what this means? Firstly, Cadsuane thinks its a sharp drop from her to Moiraine. But she's speaking in Aes Sedai terms. She may be 70 and Moiraine 60, the same kind of drop between Lanfear and Nynaeve/Semirhage. To Semirhage, that is a minor issue, no reason at all for her to be cowed by Lanfear. To Moiraine, it means the need to show a lot of deference, and for Cadsuane, the ability to be a lot more commanding.

Secondly, just a thousand years ago, there would have been 50 or more sisters stronger than Moiraine. And definitely, more women at Moiraine's level, since she's closer to the mean than those 50+ women. The Tower has been under sampling this group, and they also undersample at the lower strength levels because they reject anyone weaker than Daigian, and may not even invite to the Tower those who don't spark and are detected to be too weak. Daigian is an incredible rarity in the Tower, not common at all. She's like the Cadsuane of weak Aes Sedai. They talk about her as much for her weakness as they do about Cadsuane's strength. And there are likely as many women as Cadsuane at the negative distance from strength 50 as Cadsuane is positive.

Think about it: Cadsuane at 70 is 20 above average of 50. A woman 20 below will be strength 30, probably just at the edge of being accepted Aes Sedai. Go one step higher, and you get Egwene, an incredible rarity in the Tower, at strength 75. How many at strength 25 do they even get? They turn these women away, of course, but are they in greater number than a woman of Verin's strength in the wider population? I doubt it.

Depends where you place the average, actually. In Linda's list, the numbers between Verin and Leanne are the most populated.

Except, of course, it completely doesn't fit with anything RJ said. It fits your version of his quotes, not his actual quotes.

Incidentally, I place Elaida at 60, and Daigian somewhere in the low thirties. Meaning I put her at about 50%, slightly more, of Elaida's strength. We aren't incredibly far off...