They never overpowered Cassandra and in order to trick her they had to use Searebro. And she was manipulating an entire military force in the last 2 issues too. And in the last issue head on she took the entire team fairly handily until they dosed her with nanites
They also couldn't dent her head on so they had to resort to Magneto helmets and then hit her with nanites in the end.
Telepathy wise she was still well above both Rachel and Jean in Red. The issue in Red was not her power level it was that she was an idiot. She waited a whole week for them to manufacture Magneto helmets