*Feanor,Turin and the Second Prophecy of Mandos*

[Maédhros]

I would be possible to skip the "all" but, in the original it were all Elves of the West which would incloud all those that lingered still in Middle-Earth. Thus in the original the knowledge was not restricted from Middle-Earth and I would not do so in our version. We have in addition not in any way made clear to which date the Words reffer. Thus it could reffer to the later ages when Numenor was no more. With all that I can't seen a forcing reason to restrit the rumor to the numenorens by skiping "all".

I would skip the all just based on the fact that by not saying all, we are not saying per se that it was not know to all Men, that is left ambiguous.
And besides that it could be argued that there were different traditions among Men because of the fact of the different Houses of Men that established themselves in Númenor.
From Morgoth's Ring: Athrabeth Finrod Ah Andreth

Another wise-woman, though of a different House and different tradition, was Adanel sister of Hador. She married Belemir of the House of Bëor, grandson of Belen second son of Bëor the Old, to whom the wisdom of Bëor (for Bëor himself had been one of the wise) was chiefly transmitted. And there had been great love between Belemir and Andreth his younger kinswoman (the daughter of his second cousin Boromir), and she dwelt long in his house, and so learned much of the lore also of the 'people of Marach' and the House of Hador from Adanel.

Good to have you aboard Fingolfin II.