When i use CActiveForm i do not relay on the weblogroute, I just look at the XMLHttprequest in firebug. And i never saw the weblogroute interfering with the returned json object. Unless you use the ‘render()’ method to return the JSON object from the controller instead of simple print/echo or renderPartial.
I know the Yii::app()->end() call raises the onEndRequest event, But not sure if that is the one registering the cweblogroute. Most likely, No. As the CWebLogRoute is shown on web pages and probably when using CController::render(). I don’t think that’s the reason. You showed the ajax validation function, What about the actual controller action?