most books you will find in the general marketplace will provide details of piano construction that are generally shared or in common with most of instrument makers, and much less about what makes each company's products unique. the information will focus on the 'what' (kinds of materials) and the 'how' (methods, techniques of building) but not why some makers choose specific ways to make their instruments different. much of the stuff that makes the tier one instruments characteristically distinct is proprietary. companies in the great people's republic or s.korea went to considerable expense in some cases to buy the designs and proprietary info from failing or struggling german/central european piano makers.
the best explication of what makes and how the tier one piano builders build their limited production pianos will come from experienced technicians and dealers who've worked with many pianos intensively including visiting the factories and taking training courses for servicing specific makes. for example, a certified steinway tech had some interesting things to share on the differences between the NY factory and the Hamburg one (the company for example would not even sponsor a visit from the chief technical supervisor from hamburg to go to NY until fairly recent times in this millennium). the technician who brought our vintage piano 'up to snuff' shared some interesting details on its design that reflected how it shared characteristics more usually found in german designs, though it was made in Boston. some owners of first tier pianos have gone on factory tours and most seem to have enjoyed the experience, if the marketing of the dealers who sold them pianos can be believed. of course a buyer of a new high end piano who chooses specifications to order will get treated quite well if (s)he wants to go to the factory and look at it before it's shipped.
the gent from livingpiano.com, Robert Estrin, seems very generous with his knowledge. he's played and worked with all of the tier one pianos for years and probably knows many details he doesn't put on his videos. a resource like him is probably more informative than a book that has been published for the general reading audience.
book on piano construction design?