$wgAllowCategorizedRecentChanges has a problem: You cannot find talk page changes for the associated content NS.
Article "Foo" is categorized to "Category:Foo pages". When I filter RC by cat "Foo pages" and "all" namespaces, new comments on Article "Foo" should be listed.
The NS filter is strict tho.
Add option to connect uncategorized talk with the content NS. Best might be an option in the RC fieldset, but also a global admin var is ok imo.