These aren't really recommendations as I've not read any of them, but here are other books I'm aware of that I believe would be in the age range you're looking for. Feel free to Google for age levels in case I toss something in this group that doesn't belong.
Fr Finn books - there are six that have been printed by TAN
"Like Catholic versions of Tom Sawyer or the Hardy Boys -- but these books also teach Catholic virtues through their exciting, fun to read adventures! Includes Tom Playfair, Percy Wynn, and Harry Dee. A great portrayal of the All-American Catholic boy."
My Path to Heaven - I borrowed a copy of this to preview and wasn't fond of the writing style, but it's the right age group.
Windeatt chapter books - saint books advertised for age 10 and up
Vision Books - saint books for about age 9 and up
The Book of Saints and Heroes - I think this is out of print again, but it's an old book, so you might be able to find it free online. One of the reviewers on Amazon suggested age 12+.
Tales of Foreign Lands: Catholic Stories of Adventure in the Mission Lands - three volumes
My Catholic Faith - a catechism good for almost any age (maybe 10 on up?), numerous illustrations
The "Windeatt Chapter Books" are miscategorized for "10 and up." They are for ALL AGES. I have known 3-year olds to enjoy them. There have been many saints in the history of the Church who at a very young age, like before the age of reason, had the grace to understand concepts most challenging even for adults. Your child could be one of these. You never know how God's grace will work next.
Mary Fabyan Windeatt was a most talented writer, who took complicated and intricate stories making them understandable at a simple level.
The most prominent of these 20 books (you should have the entire 20 volume set without question!) is
The Little Flower. This is a marvelous work that serves both as a stand-alone story book for children (but based in reality) but also for
an introductory volume for adults who would like to read A Story of a Soul, by St. Therese of Lisieux. Many adults who could not understand things in the quasi-autobiography of St. Therese of Lisieux, have been most appreciative of this shorter work by Windeatt, because it explains all of the mysterious questions in the Saint's writings. St. Therese had not intended her work to be made into a book for publication, but rather it was a series of letters sent to her sister under obedience, for her sister was the Superior of the Convent where St. Therese was stationed.
It says right on the pages of this book that perhaps when the reader is a bit older (like a year or two over 5, for instance) that he might like to read the original writings,
A Story of a Soul. That is to say, now that you have read The Little Flower by Windeatt, you will be prepared to read the full version that captivated the interests of millions in the early part of the 20th century, before she was canonized in 1924. In fact, it was in no small measure the popularity of this fine book that advanced the cause for her canonization to a mere quarter-century.
(Do not make the mistake of comparing this to the literal joke of JPII's cause, which is another matter entirely. In 1924 the Church was still running on the tracks and firing on all 8 cylinders.)
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