I agree with your idea, it'd add a lot of flavour.
- How about when a engraver has a mood, besides from a very good piece of art, they randomly choose a fanciful tagged creature/object and begin sculpting a artifact engraving? Allowing the non-existing object to manifest itself in a way, divine moods should to this extent be more prophetic and accurate for instance in drawing the identities of things like gods and demons to a tee.
-Herd the engraver around by using burrows
They shouldn't send you out on quests to retrieve them though without a legitimate rumor that it actually exists in a location, as well as the option to return back and say it isn't there.
Ah, but humans don't mood. Hmmm.
To replicate the 'grail quests' that made up a fun portion of mundane medieval adventurers lives, you'd need something like a false trail of clues. Perhaps triggered when believers catch sight of a masterwork cup.
Oh, or even caused by people seeing the artwork of the artifact?
Not sure many players would follow the clues too hard if they already know there's no magic in the world. It's more something to get npc adventurers roaming about and cause pointless wars.
So...just thinking in text randomly...artwork of mystical artifacts, causes rumours, causes more widespread artwork, causes people to start taking it way too seriously and thus...procedurally generated cults triggered by the whims of a procedurally generated artist.
Which would be kind of fun as an adventurer, you follow around a group of questers on an impossible mission, getting into all sorts of adventurers along the way just to see how deep the generated cult has gotten.
And fun in site mode (presumably a town) as the art trends will clue you into potential threats from cults and other factions (long time in the future of course).