An error gave me:
You used the wrong word.
They are not allowed not to reproduce my letter.
This is clearly wrong.
Whooopsss....that was a typo....it's fixed now.
"They are not allowed to copy my letter" should have been accepted
'Copy' is used far more frequently than 'reproduce'. Can I take a copy? How many copies do you want? Photocopier.
They cannot reproduce my letter should accepted
I think they're trying to make sure we note the distinction between "may" and "can" in Indonesian. Usually in English we use "can" in place of "may" and don't make the distinction; "may" sounds formal and old-fashioned.
And the English sentence using 'may' or 'may not' is often ambiguous. It could mean 'not allowed' but also 'they might reproduce them in the future or they might not.'
I completely disagree. May and can should not be used interchangeably. They have distinctly different meanings. May I ?