There was a comment on the other gallery of this artbook mentioning missing pages.
other gallery: /g/238447/993365c01a/

edit: clarifying that the files in this gallery are uploaded from the below baidu link

Found a version including missing spreads at
https://www.moehui.com/17462.html
https://pan.baidu.com/s/1o9M13V8
"
画集包 JPG格式
链接:百度网盘 密码: 3orz
解压密码：www.moehui.com
"

That being said I'm not sure if every missing page is in this one.

The retail sites I found all included the following note
"20ページ仕様/電撃マ王 2010年5月号付録になります。"
Pretty sure the first bit means there should be 20 pages, but the last image showing a page number shows "17".

Also the table of contents on the first spread page

"
イラストギャラリー 狼と香辛料と麦と林檎と P. 2
スペシャルインタビュー 狼と香辛料と小梅けいと P. 18
"
mentions a "special interview" on page 18

At first I thought that was the very last page, the one with Nora and her dog, but that page isn't numbered and those commentary blurbs from Koume Keito (小梅けいと) are on every page, so I don't think that's the special interview. Transcribing the bold text of the very last page tells me this image is a purchase bonus
"初出/電撃コミックス狼と香辛料IIIまんが王購入特典カード"

小梅老師 (＊゜ー゜)ｂ

Base +7

best mommy

Base +8

Delicious apples and wolf

Base +10

Upload all the pages and not just the missing ones. This will be the new version of the gallery and we can replace the old one.

Go to manage galleries, and then clone/unlock and then add the rest of the pages. I can't download from baidu so I can't do this myself.

Base +8, blabbo +6

@do_it_again_chen
There's been a misunderstanding. This is the all the files from the baidu gallery/zip. I downloaded/uploaded the files in this gallery from the link.

Base +9, blabbo +6

Okay.... besides the toes... This was a nice little gallery.

Base +6