The 1858 Raccolta was translated by Ambrose St. John, the companion of Cardinal Newman. They both went to Rome and Ambrose was granted permission by the Pope to translate the Raccolta which had only be written in Latin and Italian up to that time, into English. Thankfully he included all the Popes who had indulgenced each devotion so we can see how far back it goes.
In the introduction he states that EVERY docuмent in Romes states that the indulgence is FOREVER. Also the docuмents read YEARS not days.
I've compared the site below to an original book (it has not yet been reprinted) and found it to be accurate except for a couple spelling mistakes Also the original has additional prayers in the back as it was to be used as a prayer book.
www.liturgialatina.org/raccolta/contents.htm