As with the original @f_bu 's script, it creates a copy of your master file and adds the corresponding taxonomies. It does not update existing taxonomies. The resulting file is not meant to be the master file. You should keep using your original file and generate the new one whenever you want to see the classification. This should be seen as a workaround. The real solution would be to have some kind of integration with PP.
In relation to stocks, unfortunately, it only works with funds and etfs, I am afraid it currently will raise an error with single company shares.