I believe you're reply is a little misleading - playing with words here. I'm certain there are no 'updates' as such to 10.5.8.
Are there any "improvements" one can make when using that OS? Yes indeed! Using webkit and TenfourFox as you state are improvements for web use, and well worth having.
The question was
”Is there any unofficial updates/patches or fixes for 10.5.8?”. Yes, there are. The scripts update the system certificates and enables advanced features. That is not misleading or playing with words, those are facts.
But I suppose you limit this topic to more formal updates including the installer, or what not.
Nonetheless, the question in itself did already make room for my answer with words like ”patches” and ”fixes”. I really don't understand why you object. Perhaps a question of language.
And I didn't mention Tenfourfox, since it does nothing for the operating system itself. Nor does Webkit.