As I mentioned above And it is not possible to change the URL as you want within Toolset,
And you are right, "author_link" hook can not works in your case,
There is another hook author_rewrite_rules should works for you:
http://codex.wordpress.org/Plugin_API/Filter_Reference/author_rewrite_rules
And there are a lots of posts in google are talking about it:
for example:
http://wordpress.stackexchange.com/questions/17106/change-author-base-slug-for-different-roles
Hope it help