After working with this mod for three weeks, I have dropped the Google Sitemap method suggested by the vBSEO team. That method, well intended, was a quick "kludge" which was not optimal for this type of application.
What I have done is easy and requires a small bit of manual labor and goes something like this:
- Copy the *xml.gz files from ./vbseo_sitemap/data to another directory, for example FORUMROOT/es for Spanish, FORUMROOT/ja for Japanese, FORUMROOT/zh-CN for Chinese etc.
- Unzip the files and use sed to add the ?hl=ja (or whatever flag you want to do) to each URL in the Sitemap. This takes about 10 seconds.
- Update sitemap_index.xml.gz the same way, or use VI, etc.
- Submit this Sitemap to Google.
- Copy the first one you did and repeat for as many languages as you wish.
This method has many advantages.
First of all you have a completely different sitemap of your entire site for each language. So easy to submit to language specific search engines. Also, you can easily track the indexing progress for each Sitemap. This is much easier to manage and much cleaner, IMHO.
Of course, this method takes a bit of work when your need to update your language Sitemaps, but if you have a large board, this will get you indexed nicely in a well organized way. You can add the newer links after a high percentage of the legacy links are archived (in a few months).
We added the top 10 languages to Google Webmaster Tools, each with its own Sitemap, so where we originally had one big sitemap with nearly 396K URLs, we now have a total of around 4,750K URLs total in 11 Sitemaps. So far, Google is happy :-)
With this simple method, you can see the index progress on each language. You can submit your Sitemaps to language specific search engines. You can manage the update frequency on the translated URLs differently than your main site. You can also avoid any potential problems with your main sitemap.
(See attachment)
Enjoy and Good Luck!