Yes David. 

On further investigation, I think there are some packaging issues around "Assistive Tools" that prevent this topic from being dislayed localized in Maverick.

In short, I think the Ubuntu gnome language packs do not install the localized Assistive Tools content, which is a gnome-user-guide topic. 

Here's how it looks to me. 

Yelp looks for localized content here: 
/usr/share/gnome/help/TOPIC/LANG/

In Ubuntu, there are links installed there that point to the following location:
/usr/share/gnome/help-langpack/TOPIC/LANG

So yelp tries to open files where it expects them but actually ends up opening files that exist in another location because of the links. 

A closer look. First I'l show a topic that works, then show this topic, which is broken, for comparisoon. 

The TOPIC that works is 'newtoubuntu' and the LANG is zh_CN. 

The newtoubuntu LINK is installed by ubuntu-docs package:

$ ls -alh  /usr/share/gnome/help/newtoubuntu/zh_CN/newtoubuntu.xml lrwxrwxrwx 1 root root 64 2010-12-14 14:26 /usr/share/gnome/help/newtoubuntu/zh_CN/newtoubuntu.xml -> /usr/share/gnome/help-langpack/newtoubuntu/zh_CN/newtoubuntu.xml
$ dpkg -S  /usr/share/gnome/help/newtoubuntu/zh_CN/newtoubuntu.xml 
ubuntu-docs: /usr/share/gnome/help/newtoubuntu/zh_CN/newtoubuntu.xml

The newtoubuntu LINK TARGET is installed by language-pack-gnome-zh-hans-base:

$ ls -alh  /usr/share/gnome/help-langpack/newtoubuntu/zh_CN/newtoubuntu.xml 
-rw-r--r-- 1 root root 49K 2010-09-20 04:59 /usr/share/gnome/help-langpack/newtoubuntu/zh_CN/newtoubuntu.xml
$ dpkg -S  /usr/share/gnome/help-langpack/newtoubuntu/zh_CN/newtoubuntu.xml 
language-pack-gnome-zh-hans-base: /usr/share/gnome/help-langpack/newtoubuntu/zh_CN/newtoubuntu.xml

This works. That is, one sees localized "New to Ubuntu" on the front page of the Ubuntu Help Center displayed in yelp.

Now lets look at broken TOPIC gnome-access-guide ("Assisitive Tools").

The gnome-access-guide LINK is installed by gnome-user-guide-zh package:

$ ls -alh /usr/share/gnome/help/gnome-access-guide/zh_CN/gnome-access-guide.xmllrwxrwxrwx 1 root root 78 2010-12-16 14:45 /usr/share/gnome/help/gnome-access-guide/zh_CN/gnome-access-guide.xml -> /usr/share/gnome/help-langpack/gnome-access-guide/zh_CN/gnome-access-guide.xml
$ dpkg -S /usr/share/gnome/help/gnome-access-guide/zh_CN/gnome-access-guide.xml
gnome-user-guide-zh: /usr/share/gnome/help/gnome-access-guide/zh_CN/gnome-access-guide.xml

The gnome-access-guide LINK TARGET is not installed by ANY package:

$ dpkg -S /usr/share/gnome/help-langpack/gnome-access-guide/zh_CN/gnome-access-guide.xml
dpkg: /usr/share/gnome/help-langpack/gnome-access-guide/zh_CN/gnome-access-guide.xml not found.
$ cd /usr/share/gnome/help-langpack/gnome-access-guide/zh_CN/
bash: cd: /usr/share/gnome/help-langpack/gnome-access-guide/zh_CN/: No such file or directory
$ cd /usr/share/gnome/help-langpack/gnome-access-guide/
bash: cd: /usr/share/gnome/help-langpack/gnome-access-guide/: No such file or directory
$ cd /usr/share/gnome/help-langpack/

Even though I have what would seem to be the right lang packs installed:
$ apt-cache policy language-pack-gnome-zh
language-pack-gnome-zh:
  Installed: 1:10.04+20091218
  Candidate: 1:10.04+20091218
  Version table:
 *** 1:10.04+20091218 0
        500 http://us.archive.ubuntu.com/ubuntu/ maverick/main amd64 Packages
        100 /var/lib/dpkg/status
$ apt-cache policy language-pack-gnome-zh-hans
language-pack-gnome-zh-hans:
  Installed: 1:10.10+20100930
  Candidate: 1:10.10+20100930
  Version table:
 *** 1:10.10+20100930 0
        500 http://us.archive.ubuntu.com/ubuntu/ maverick/main amd64 Packages
        100 /var/lib/dpkg/status
$ apt-cache policy language-pack-gnome-zh-hans-base
language-pack-gnome-zh-hans-base:
  Installed: 1:10.10+20100930
  Candidate: 1:10.10+20100930
  Version table:
 *** 1:10.10+20100930 0
        500 http://us.archive.ubuntu.com/ubuntu/ maverick/main amd64 Packages
        100 /var/lib/dpkg/status


IN SUMMARY: the lang packs are not installing the localized gnome content for at least this topic.