Why would I trust the ECF's over the writers of Catechism?
The Catechism represents 2,000 years of Catholic theology, including the thoughts of the ECFs. But also the Ecumenical Counciles and later theologians.
It was promulgated by Pope John Paul II who wrote:
The Catechism of the Catholic Church is the result of very extensive collaboration: it was prepared over six years of intense work done in a spirit of complete openness and fervent zeal.
In 1986 I entrusted a commission of 12 Cardinals and Bishops, chaired by Cardinal Joseph Ratzinger, with the task of preparing a draft of the catechism requested by the Synod Fathers. An editorial committee of seven diocesan Bishops, experts in theology and catechesis, assisted the commission in its work.
The commission, charged with giving directives and with overseeing the course of the work attentively followed all the stages in editing the nine subsequent drafts. The editorial committee, for its part, assumed responsibility for writing the text, making the emendations requested by the commission and examining the observations of numerous theologians, exegetes and catechists, and above all, of the Bishops of the whole world, in order to improve the text. The committee was a place of fruitful and enriching exchanges of opinion to ensure the unity and homogeneity of the text.
The project was the object of extensive consultation among all Catholic Bishops, their Episcopal Conferences or Synods, and of theological and catechetical institutes. As a whole, it received a broadly favourable acceptance on the part of the Episcopate. It can be said that this catechism is the result of the collaboration of the whole Episcopate of the Catholic Church, who generously accepted my invitation to share responsibility for an enterprise which directly concerns the life of the Church.
Of course it is not an infallible documents (although it will contain infallible statements from Ecumenical Councils) but then the ECFs were not infallible either.