No, “Montblanc CS1” is not a new edition of the older standard works but a book in its own right. It appeared in 2014 and covers the years 1908 to 1947, that is, the early history of the company and its models. The abbreviation picks up on “Montblanc Collectible Stars”, which collectors know as CS2. The third reference in common use is the large-format grey volume “The Montblanc Diary & Collector's Guide”. The titles complement one another, because they cover different periods and have different emphases.
There is also a Montblanc book published by Danish collectors that has been available for some time. For identifying and dating older models, printed works of this kind remain the most reliable source, since they record catalogue illustrations, model numbers, nib variants and production periods systematically. Information scattered about the internet, by contrast, is often fragmentary and of uneven quality.