请教一个英语语法题：散文佳作108篇中贾平凹的丑石英译中有这样一段：It gave us

请教一个英语语法题：散文佳作108篇中贾平凹的丑石英译中有这样一段：It gave us
散文佳作108篇中贾平凹的丑石英译中有这样一段：It gave us a great surprise!We had never expected that such a strange and ugly stone should have come from the sky!So it had once mended the sky,given out its heat and light there,and our ancestors should have looked up at it .
在此有两个should have…..根据原文应该是表推测或可能的意思，但上学时老师教的是本应做….的意思，是译者用错了，还是should have也有推测的意思？
另外“真看不出！它那么不一般，却怎么连墙也垒不成，台阶也垒不成呢？”译文为“I never expected it should be so great But why can’t people build a wall or pave steps with it？”中“真不看出”的译文是否有些生硬，有没有更口语化的译法？