Cora Anderson outlived Victor by more than a decade, and the years after his death in 2001 are part of why her book carries more weight today than an anniversary keepsake normally would. She continued teaching directly, and among the students who passed through her instruction were two figures who went on to become influential teachers of Pagan witchcraft well beyond the Feri Tradition itself, Starhawk and Gwydion Pendderwen. Their own later work carried pieces of what they had learned from her out into the wider modern Pagan movement, which means Cora Anderson's influence on how present day Pagan witchcraft is taught runs well past the readers of her own book.
That makes the book worth reading against the oral transmission surrounding it rather than as a replacement for it. Fifty Years in the Feri Tradition was never meant to be a self-sufficient course of instruction; it is a short, personal statement correcting the gaps and distortions Cora saw building up in secondhand accounts, written by someone who was, by the time student after student passed through her teaching, in as strong a position as anyone alive to say what the tradition she and Victor had founded actually held. Read that way, the book functions less as a manual and more as a check, a founder's own account a later reader can measure any other description of Feri belief and practice against.