I don't feel like they belong to the utaite wiki though.

Actually they are important in my opinion, but just too much off topic to have personal pages for respective illustrators, as in they are not really directly related to covering songs and utattemita.

I think it's important to at least mention them somewhere if you're going to use the images /on/ the wiki, though. Provided that information is available.

Well, they are mentioned on the Avatar Illustrators page, aren't they? And the utaite they draw for are also mentioned, and even their external websites along side an icon with a part of their work.

Even if we were to create individual pages for them, I can't see, what you would put on those pages. All their works? That's what they have their gallery for. (Pictures are a universal language, unlike Japanese, French or English)

Well adding on to what Bluebird said

Firstly, we mention/credit the illustrator everywhere the image by said illustrator is used. I don't know how it can mentioned more than that. 

Secondly, there's not much content to put an illustrator's page since well what could you even say?

-He/she draws a lot for x utaite
-He/she draws a lot of choruses

Are pretty much that main things that could be said about an illustrator which most of them don't even fit since more often than not, they're just "one time illustrators"

You could technically describe an illustrator's art style but...illustrators tend to have more than one and it seems kinda redundant to do so anyway when you can just look through their gallery (vs. utaite which you have to listen to a lot of covers slowly to get more of their vocal information so to say).

I mean I love illustrators too and they deserve more recognition but I think the Avatar Illustrators page which Bluebird linked is sums up the illustrators enough.

(Also sorry if I sound condescending >.<;; I'm not trying to be)