The German magazine Der Spiegel has repeated the allegation and claims to have seen the evidence supporting the claim that Cardinal Ratzinger gave permission to reprint the article… but in a magazine, and not in the book mentioned in the first post.
In 1997, Ratzinger – who at the time was head of the Vatican’s Congregation for the Doctrine of the Faith – allowed Austrian publisher Aula-Verlag to use a text that he had written for a collection of essays to mark the 150th anniversary of 1848, a year of revolution in Germany as elsewhere. The editors of this book entitled “1848 – Erbe und Auftrag” (1848 – Heritage and Mission) were Otto Scrinzi and Jürgen Schwab, two well-known leading figures among German-speaking right-wing extremists who have never made a secret of their political beliefs
On Sept. 18, 1997 Reisegger asked “His Eminence Joseph Cardinal Ratzinger” for “permission to reprint” the article that was published in the magazine Communio in 1995. "The monthly magazine Aula of the Libertarian Academic Associations of Austria " wanted to comment on Ratzinger’s “exceptional thoughts” on the “confusion” surrounding the 150th anniversary of the Revolution of 1848.
Only 12 days later, Ratzinger’s secretary, Monsignore Josef Clemens, gave Reisegger the green light: “In response to your friendly letter … I may on behalf of Cardinal Ratzinger inform you that he has approved the printing of his essay … in the monthly magazine Aula of the Libertarian Academic Associations of Austria.”