ewtn.com/library/CATECHSM/PIUSXCAT.htm
"To my knowledge, the Catechism of St. Pius X has never been published in English in its original text.
There is one Catechism of Christian Doctrine, published by the Rev. Msgr. Eugene Kevane in Virginia, USA in 1974, but in fact, it contains a much later text which lacks much of the original text: it is the translation of the Catechismo della Dottrina Cristiana, the standard Italian Catechism, as it was in 1953.
That Italian Catechism is in turn, a summary and reduction of the original Catechism of St. Pius X.
The American edition in 1974 has further been “adapted according to the Second Vatican Council”, thus losing much of the value of the original text (e.g. expressions like “Soldiers of Christ” are suppressed from the teaching on the effects of Confirmation).
The only book where I was able to find the authentic text is the excellent Compendium of Catechetical Instruction by the Right Reverend Monsignor John Hagan, first published in Dublin in 1910, and containing for each chapter of the Catechism the relevant part from the Catechism of the Council of Trent, the questions and answers of the Catechism of Saint Pius X and Father Raineri’s Catechetical Instructions, which were very popular in the nineteenth century."
If that is the title you are looking for, see:
amazon.com/compendium-catechetical-instruction-John-Hagan/dp/B00085GN5I