It is a fact that children who receive the compulsory courses spend a larger propotion of time interacting with their teachers so that teachers play a vital role as students grow up.

此句没错，为何要改呢？

so that 引导“结果状语从句”，不是目的状语。所以谓语动词无须加can，这里teachers 是泛指，不是特指，不加the。 so that 从句是针对spend...的结果状语从句。

为了理解方便，去掉 It is a fact that， 换成In fact，把外置的主语从句改为主句：

In fact, children who receive the compulsory courses spend a larger propotion of time interacting with their teachers so that teachers play a vital role as students grow up.

【翻译】事实上，接受义务教育的儿童有更多的时间和老师打交道，所以，老师在学生成长过程中起着重要的作用。

Expert 的修改、理解和翻译，均存在错误。这个句子是说“老师在学生成长中的重要性”，而不是“师生交往多，目的是让老师发挥作用。” 理解直接失误！