Brandon said that with Cyndane "what you see is what you get." Brandon shot down any ideas that the DO was playing with Cyndane's strength. But that only eliminates the DO's role with Cyndane. After that interview, I think it highly likely that the DO was giving Lanfear a boost.

The confusion seems to surround Brandon's misconception about why Cyndane is weaker. Brandon originally thought the DO might be playing with Cyndane's strength. I believe the DO was probably playing with Lanfear's strength...just like Brandon hinted: "here's a little extra" as long as I'm pleased with you.

What I think happened is that Lanfear WAS the strongest possible channeler because she was getting a boost from the DO in some way. Heck, it might not even be fair to place Lanfear on the 21 level list. Maybe she occupies a level all of her own above everyone else b/c of the boost from the DO to ensure she was the strongest. Brandon mistakenly assumed Cyndane was being affected by the DO in a similar way to Lanfear, but obviously in the opposite direction, and this is what caused the confusion and discussion between him and Maria. Maria needed to point out to Brandon that it wasn't the DO messing with Cyndane's strength, but instead the DO was playing no role in reducing Cyndane's strength.

I think this is what most likely happened. I can say one thing: I'm excited to find out the answer in the next book!