Carolyn Keene is the pseudonym of the authors of the Nancy Drew mystery stories and The Dana Girls mystery stories, both produced by the Stratemeyer Syndicate. In addition, the Keene pen name is credited with the Nancy Drew spin-off, "River Heights and the Nancy Drew Notebooks.
The Nancy Drew series were not written by a woman named Carolyn Keene
The context says that Carolyn Keene is the pseudonym used by multiple authors. So, the books were not written by a woman named Carolyn Keene. That is just the name used in place of the real authors' names. The system was likely unable to understand what the context was really saying. 