It may be that HTMLEditor has created a new (duplicate) directory for its files. The page code you posted shows the HTMLEditor folder as being inside the webassist directory, which is presumably in the root directory of your site.
Was your original HTMLEditor folder in a webassist directory? Do you now have two HTMLEditor directories? This can happen if an instance is originally created inside a folder in the root directory and is subsequently edited, and would also create your exact scenario if you have installed CSSFormBuilder2 since creating the original editor instance.
If you could confirm whether this is/is not the case, it would clear the way for a proper diagnosis.