This Flame of Love book that you requested is provided to you in the hope that you will prayerfully decide to devote your life more fully to Jesus through the Immaculate Heart of Mary.The letter states that the Archbishop of Esztergom-Budapest and President of the Council of Episcopal Conferences of Europe, Cardinal Peter Erdo, gave an imprimatur to the Hungarian manuscript of the Spiritual Diary of Elizabeth Kindelman, "authoring the publication of the messages given to her by the Lord Jesus and the Blessed Virgin Mary." The letter continues, "These Heavenly communications, given between the years 1961 and 1982, are consigned in her Spiritual Diary at the request of the Lord Jesus."
The letter further states: "These messages are urgent and emphasize the 'same' messages as most of the other church approved messages from Anika, Betania, and elsewhere. The Lord states: 'The Grace from the Flame of Love of My Mother's Immaculate Heart is Noah's Ark.' We believe these messages from God are the most important of all so far since Fatima as there is a signal grace intended for each person and we are asked to pass it to others."
I have read much of the book and find it inspiring. The Flame of Love does have an imprimatur by Archbishop Chaput. While an imprimatur does not mean that the Church official approves the apparitions are true, it means that no items in the book are contrary to Catholic teaching.
While I can find little online regarding these apparitions and whether or not they are officially approved (or at least not condemned), this book does contain some spiritual wisdom and an example of holiness and trust in God's providence as seen through Elizabeth Kindelman.
Holy Mary, Mother of God, pray for us! Help us to pray the Rosary daily as you have asked!