Some scripts on http://www.creationkit.com have (requires 1.6) beside them. I have latest versions of both the game and editor. But can't use that script. What's going on?

Some Functions/Events/scripting methods won't work with prior iterations. OnPlayerLoadGame, for instance, was introduced by the 1.6 patch, so anything using it will not work with anything less.

But my version is 1.6.89

v1.6.89 >= v1.6. Anything that "requires v1.6" means 'Requires v1.6 or later' given it's unlikely Beth would add a function and later remove it.

I do not see, however, why these scripts do not work if i have the latest versin of the editor

Scripts are separate of the editor, so only the Skyrim version matters. Post the [spoiler][/code]code[/code][/spoiler]?