I noticed that if the URL for a bookmark doesn't have a favicon assigned, e.i. https://appleloan.citizensbank.com, (Website without a favicon) the script will run and tell you that it did its job but Safari won't show you the icon selected, just the standard icon with the initials of the website. The script though creates an icon image in the Cache/Icons folder but Safari won't display it.
The script works fine with icons without a favicon assigned. the problem in your case is the URL. At the moment Favtool work only for favorite sites not for bookmarks. support to bookmarks will be added in 2.1
I noticed that if the URL for a bookmark doesn't have a favicon assigned, e.i. https://appleloan.citizensbank.com, (Website without a favicon) the script will run and tell you that it did its job but Safari won't show you the icon selected, just the standard icon with the initials of the website. The script though creates an icon image in the Cache/Icons folder but Safari won't display it.