Hi,
The thing is that the element which you are trying to retrieve is created in DOM after onAfterRendering method is called. It is created once the control get a model data. You can add a css class in function of formatter like this:
tourStateTitle: function (value) { ... this.addStyleClass("nameOfClass") ... // If the class is not added to the element what you want, you can try:
// this.getParent().addStyleClass...
},