He did not regret saying what he did but felt that he could have expressed it differently.

问题描述:

He did not regret saying what he did but felt that he could have expressed it differently.

他并不后悔说了他做过什么,但是感觉他本可以表达的不同一些。

意思是:
他并不后悔说出他干了些什么,只是觉得自己应该换一种方式来表达.
“could+have+done”是虚拟语气,表示对过去事情的假设,意思是本来能够做某事而没有做.