Does the sentence "She said she would have lunch with Susan tomorrow" break the law of the future in the past?

Question

Learnenglish.britishcouncil says:

“I work in Italy” Reported speech: He told me that he works in Italy.

It isn’t always necessary to change the tense. If something is still true now – he still works in Italy – we can use the present simple in the reported sentence.

That is simple present tense, what about other tenses such as future tenses?

Let say today is Monday & at 1 PM, A says "I will have lunch with Susan tomorrow".

Ok, at 2 PM, the time is still true,

Can B say "She said she will have lunch with Susan tomorrow"?

or B must say "She said she would have lunch with Susan tomorrow"? ("will" must be changed to "would" no matter the time is still true or not)

The problem is that when we say "She said she would have lunch with Susan tomorrow", we break the law of the future in the past.

This site said:

The future in the past is used to look into the future from a point of time in the past. However, this "future" event still occurred at a time before the present time.

E.g. I woke up (1) at 8am yesterday. I was meeting my boss (2) at ten o'clock that morning, so I wouldn't be able to have lunch (3) with Susan. I wasn't going to get home (4) again until late that night.

(2), (3), (4) are all the future in the past & they had to occur before now.

However, if B says "She said she would have lunch with Susan tomorrow", then the event has not happened yet.

Note: Cambridge Grammar said:

We don’t need to change the tense in indirect speech if what a person said is still true or relevant or has not happened yet. This often happens when someone talks about the future, or when someone uses the present simple, present continuous or present perfect in their original words:

He told me his brother works for an Italian company. (It is still true that his brother works for an Italian company.)

She said she’s getting married next year. (For the speakers, the time at the moment of speaking is ‘this year’.)

He said he’s finished painting the door. (He probably said it just a short time ago.)

She promised she’ll help us. (The promise applies to the future.)

So, Does the sentence "She said she would have lunch with Susan tomorrow" break the law of the future in the past?

Answer 1

These distinctions are simply guidelines but not hard-and-fast rules. The shift of tense does not indicate that the event has not taken place.

Let's say that she agreed last week to have lunch with Susan today, to discuss a business proposition. The lunch does take place. She has a sandwich. Susan has soup. If the question is about what she said, it doesn't matter whether the lunch took place or not:

When I spoke with her on the phone, she said she would have lunch with Susan today, and they did indeed have lunch. She's a woman of her word.

Not needing to change the tense when the assertion is still true does not imply the corollary that changing the tense means the assertion is now false:

He said his brother worked in Milan.

His brother may still work in Milan. The shift of tense signals that the speaker is reporting the speech of another, not making the assertion himself.