We know Egwene is a little less 2x Moiraine at maximum potential, but we don't know how close to her potential she as at the time of Moiraines comment. It's only a handful of weeks after TSR and her forcing is nowhere near as intense in that timeframe as it was when she was a damane. Aviendha had only been channeling for a few weeks and while obviously the WOs are much more aggressive coupled with Egwene being there to push her it's clear she gained strength rapidly, but it's practically impossible for her to be as strong as Moiraine at this time. Elayne was not as strong as Moiraine at the end of TSR or she would not have been surprised by her ability to lift a single woman in the Panarchs palace and we know by the time she and Aviendha become 1st Sisters they are pretty close to each other.

Now consider how strong they would need to be for Moiraine to think they could overwhelm a Forsaken. She likely isn't counting training into her equation as we all know even if they were 2x Lanfear they would realistically stand no chance, Alivia proves that. But in making her point on how strong the Forsaken are she'd have to think they were at least 20% stronger than Nynaeve to make such a statement and believe it. Makes me believe Moiraine is in the ballpark of 50% of a Forsaken female.

Egwene has much more knowledge of what to expect from a Forsaken when she ponders linking with Romanda and Lelaine to match one of the men Forsaken and knows she'll need a significant strength boost to face someone with exponentially more knowledge than her so she thinks she'll need to more than double her own Strength to face someone like this. However, by TOM, she confident in her skill and strength comination that she could face and defeat Mesaana the non-warrior Forsaken on her own. Odds are she has continued to grow in strength and she is clearly vastly more skilled than when she made the comment about facing a male Forsaken.