60 levels below Kerene, I think. The highest Aes Sedai level pre-wonder girls was Elaida/Moiraine/Siuan. Kerene and Meilyn were above this, as was Cadsuane (who we know is just below the Wondergirls in strength). the text makes clear Cadsuane is definitely stronger than Nicola (since the Aes Sedai say no one with Cads strength had been seen in a thousand years, and it was only a few hundred for Nicola). Nicola may then be as strong as Kerene, or there may be a level or two between them. That'll become clearer when we have the entire book, since each Aes Sedai entry has their old and new strength levels, and this includes bit players like Serafelle (based on entry 2). Comparing Nicola to Kerene and Mailyn will clarify this.

As I read it, 60 total strength levels before Wondergirls. 12 more added after, and this includes Foresaken.

Definitely not, since the top strength level (Level 1) is said to be as strong as a woman can get, and equal to the strongest man. Since Sharina, at least, is definitely stronger than Nynaeve in potential, there's no way Nynaeve is at level 1.

There does seem to be some bunching up at the bottom, but that should be clarified when we get a large number of actual ages for the Aes Sedai and a factor for how the Oath Rod cuts age.

Clear how? Moiriane is nowhere close o Lanfear's level of knowledge, experience, and skill. Would a Moiraine strength Aes Sedai from the Age of Lengends be as held back as she is? I really really doubt it.

Based on what evidence? If anything, the opposite seems true. Somewhat weaker channelers are able to achieve all sorts of effects a stronger one could.

Evident implies evidence. Where is it?

Again... why so?

Did I miss something in the books? I don't think we've ever seen her launch a fireball on her own, because she's never been in the situation to. She did, however, pass the Aes Sedai test, which she couldn't have by "barely launching a fireball", since some of those weaves are actually not very different from Fireballs.

I'm mystified by the authority with which you assert this. Where did we see a sizing of their fireballs?

The only case we have of strength to actual effects is with Siuan. Old strength, she could comfortably lift three times her strength. After becoming weaker (but still above the strength of Daigian, so it is ambiguous for now where exactly she is) she cannot lift Gareth Bryne, so even a little above her weight is impossible for her to lift. Per Terez, Daigian was at level 45(33 old). So Siuan went from level 13(1) to somewhere like 40, or below. Working off 40, she went down 27 levels in strength, about a 40% reduction in strength. If Bryne weights 1.5 times what Siuan does, she went from lifting 3x her weight to not being able to lift about 1.5 times her weight, a 50% or so reduction. Seems to track quite closely.

No, but the text of the books does give hints.

That's a pretty bold statement considering these people had access to not just this list, but all sorts of other info, including individual character comparisons, to understand this issue from.