Edited answer:
The only way I have found to localize your second child pane plist file in the settings bundle is to do it by hand.
I have just tested this and it works:
When you open the Settings.bundle
in Finder, in each language.lproj
folder, make a copy of the Root.strings
file and rename them to NewInfo.strings
(for example).
Once you have one this, you should see in Xcode that there are these new string files inside your settings bundle.
Now in your NewInfo.plist file, make sure you have a field called StringsTable
and set the value of that to NewInfo
(or whatever you called your new strings file).
I have just tested this in Xcode 4.2 and the localization works perfectly:
Here is a screenshot of the Root.plist where I have added a "TEST" row to open child pane. Notice the other NewInfo.plist and the associated strings are in the correct lang.lproj folders (again, i put them there manually in Finder).
Now here is the NewInfo.plist with the StringsTable key that corresponds to the associated .strings filename:
Here are the values of the strings files in FR and EN:
And the resulting settings page in the Simulator in both FR and EN, showing that the localization works: