Came/ Had Come?

zafar142003She told me that he had come home late that night.

Past perfect use is not correct in the sentence.
"she told me" is a reported speech, not an event.
"He came home late..." is one simple past event. So "came" is sufficient.

What if I had to convert this into reported speech?
She said to me, " He came home late that night."
Will it be:
She told me that he came home late that night.

zafar142003What if I had to convert this into reported speech?
She said to me, " He came home late that night."
Will it be:
She told me that he came home late that night.

That' will be my answer.

Because both events are in the past, all you really need is She told me he came home late last night.

dimsumexpressHe came home late..." is one simple past event. So "came" is sufficient.

Why does this mean we don't backshift?

Is there a rule I'm not aware of?

Grammar GlitchBecause both events are in the past, all you really need is She told me he came home late last night.

I don't think this is right. You're meant to change the tense (of the subordinate) to the past perfect.

No, you really don't. Backshifting when the event is in the past already is optional. It's neither wrong to leave it in the simple past nor wrong to backshift. Either is okay. Really.