Changing or not changing times in reported speech

[Sb70012]

A. "Must you leave now?" he asked us. He asked us if we had to leave.
B. "Must you leave now?" he asked us. He asked us if we had to leave then.

Hello,
What happens if I don't add "then" at the end of the sentence A?
I sometimes see that native English speakers do not use or change or backshift times in their indirect speech.

e.g.

now => then
tonight => last night
today => yesterday
tomorrow => today
etc.

In my sentence A isn't it wrong if I have not changed "now" to "then" at the end of the sentence? Isn't it a mistake?

Thank you.
_________________
Sorry if I don't thank you more than once. I don't want to bother you by filling up a thread with multiple thank yous.

[Beeesneees]

The reason for leaving out 'then' is actually to avoid confusion regarding which point we are talking about when reporting at a later time.

Reporting using direct speech:
Before we left he asked us "must you leave now?" << Here 'now' indicates the time at/just after which he spoke to you.

Reporting without direct speech:
Before we left he asked us if we had to leave.
Before we left he asked us if we had to leave then. << Here, 'then' indicates the time before you left when he spoke to you.
-there is no significant difference in the meaning of these two sentences. The speaker has probably simply decided to avoid any confusion about the use of 'now' or 'then' by ignoring it completely.
_________________
"Inside every old person is a young person wondering what happened."
Terry Pratchett

[Sb70012]

Thank you but in text book grammar exercises or university exams about such sentences, how should we know that we should change the time or leave it out?
As "now" and "then".
_________________
Sorry if I don't thank you more than once. I don't want to bother you by filling up a thread with multiple thank yous.

[Beeesneees]

If it's a grammar exercise, you are likely to be expected to change it (so that you demonstrate you know the difference).
_________________
"Inside every old person is a young person wondering what happened."
Terry Pratchett

[Anglophile]