I saw this book mentioned a few times in The architectural models of Theodore Conrad (ISBN 978-1350152847) and I was intrigued enough to find a copy. It was originally published in 1968 but it has been completely revised for the 1978 edition. This is sort of academic now because software available to the architectural profession has made model building almost redundant but clients of large commercial estates probably still need to see, for prestige reasons, their potential property in miniature.
Jank's book is essentially visual with comprehensive deep captions explaining the images. Each spread has German text on the left-hand page and English on the opposite page. The emphasis is really on large projects like housing estates, business parks, or airports, rather than individual houses or single commercial properties. The photos are mostly bird's eye views of the models.
The book is probably more of a curio for architectural model makers.