I'm struggling to get my head around the Imperial Library, even if it probably is pretty simple.

I searched, for example, "ehlnofey" and got LOADS of different results, some of which being basic race profilling and articles found in games/books and expanded and elaberated on, to what just seemed to be fan fiction. That's confusing me.

How does all of this get added to the Elder Scrolls lore if it is not in an official source such as the games, in-game books or novels? How can it be added independently online? Do the developers have any say? If not, how can it be considered as legitimate?

And while we're at it, 'C0DA' is being thrown around a lot lately. What is it?

Unless you're including the forums in your search (they're now excluded by default), you're not finding any fanfic. Everything on TIL proper comes from the games, supporting materials, and the debs themselves.

If a search comes up with too many results, I recommend either using the topics sorter (top of the main menu) or the advanced search to narrow down your criteria.

Firstly, TIL has http://www.imperial-library.info/forum, and if your questions refer to their site you might be better off asking them there.

Secondly, in case you're not aware, the Imperial Library is maintained by fans, not the developers of the games. Some of the content there is summaries, speculation or exploration compiled by fans, and you may need to check the author and what section of the site an article is in if the source is of concern, but it should always be given.

On unofficial sources: well, here's the thing, Bethesda has very rarely given word on what we should consider official. What texts developers write outside of the games, or even what fans can come up with, can often be very useful in exploring concepts in lore even if you don't take it as concrete truth straight away. The officialness of a piece is often unimportant, and debate around it usually pointless. A thing can be considered on its own merits, without bothering about who endorses it.

And what C0DA is: there's a few recent threads that asks that, you can search for them. And http://c0da.es/t/c0da's a link to the thing itself. It's a text by Michael Kirkbride, with illustrations by various artists on another section of the site, which explores themes from Morrowind and the http://www.imperial-library.info/content/loveletter-fifth-era-true-purpose-tamriel, as well as implicitly confirming ideas that the "canon" of TES is irrelevant by comparison to personal interpretation.

I tried the same search and everything that was returned was either an in-game text, a Dev-written obscure text, a summary article, or something from the Forum Scholars Guild.

The last is a good point, however. The main page for FGS articles has a clear disclaimer that the articles are fan-written, but if you go straight to a particular article with the search function you don't see that and can easily get confused about the source. Though the FSG texts are well-researched and respected, they are definitely speculative and given that TIL is used as a collection of official and obscure texts, there's certainly potential for confusion. I think it wouldn't hurt to put the disclaimer from the Forum Scholars Guild landing page at the top of the articles individually so that people bypassing it with the search function understand where what they are reading is coming from.