Alas, it does seem to be not unfamiliar librarian/computer jargon. Even if my hunch is that librarians and computer archivists with a better feel for English would still say 'archived.' Or 'stored/catalogued in a library,' if they absolutely had to draw an explicit contrast between a library and an archive. But that's an admittedly conservative view.
If we had a mildly cautionary usage marking for words that are less common and less recommended, I would vote for it in this case. But failing that, perhaps marking it [tech.] would at least serve to warn away the general nontechnical user.
Interestingly, a web search turns up another, evidently older, adjectival sense meaning 'having (access to) a library or libraries,' '(well) supplied with books':
It is noted that one third of the nation is ill-libraried as
well as ill-clothed and ill-housed and ill-fed. 1935. Carnegie
a tiny band of doughty scholars supervised by Dr. William Beck and housed in a Spartan but well-libraried concrete high-rise of the University of Hamburg
Each evening, wine and cheese are offered to guests in the libraried living room
committee will be made up of a public library board member, 2 county board members (one from a libraried area and one from a non-libraried area)
a strong community outcry against the recommendation to close the small library (one resident feared being "dis-en-libraried")
For me those are more attractive and justifiable, if a bit artificial.
But not necessarily worth making into a new entry. That is, I'd vote for some I've already mentioned, such as 'laizistisch,' 'staksen,' 'umschlagen' (a long list), 'ding,' etc. as higher priorities than 'libraried.' IMHO any of those, or a number of Mattx's slang phrases, would be more useful to many more LEO users. Even if hardly a soul seems to agree so far.