It is strange that she should have failed to see her own shortcomings.

It is strange that she should have failed to see her own shortcomings.

It is strange that .... 从句常用虚拟语气。这里should 作为：竟然，表达说话人感到意外。
不可以理解为should have done 那种结构。追问那就是 should 虚礼语气 然后就是 have failed to 表示完成时吗？追答对。

不对。should有多种用法，你查牛津字典可以看到。此处不是本该的意思，而是（竟然）的意思，表示出乎说话人的意料追问也就是说不是 should have done sth 句式？

很奇怪，她竟然看见了自己的缺点。