[William Cloud Hicklin]

Well, as to the survival of Numenorean lore, besides the general statement in Akallabeth that "all their learning" went down under the wave (which of course does allow for whatever Elendil's flotilla might have stowed), there is the comment in the intro to Aldarion and Erendis that it was "the single story (as opposed to records and annals) that survived at all from the long ages of Numenor before the narrative of its end."

(The Akallabeth, naturally, was Exilic; in one place Tolkien says that tradition ascribed its authorship to Elendil himself).

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Back in that old discussion, I believe my opinion turned on Bilbo having used Arnorian sources in preference to Elven ones, which required a headcanon assumption: that Elves, as immortals, didn't write "history" in a manner that would make much sense to mortals. As an example, look at Bilbo's own song on Earendil, composed in a mock-Elvish mode: if you didn't already know the story, you wouldn't have any idea what the hell was going on.