as---as 理解为:和----一样
但not so-----as 是:-----不如-----
his accurate prediction of a major downturn was not as uncanny as he led the
public to believe
这句his accurate prediction of a major downturn和he led the public to believe相比较,所以是:
他对经济危机准确的预测难度远不及说服公众相信他的预测的难度大.
理解正确,翻译只是措辞的问题