Honestly I am unfamiliar with it. Is it posted on line or published?
I worked about five years on mine, took time off of FR. When the Tolkien estate refused to allow it to be published I posted it on line and moved on. At that time it was the only comprehensive full Tolkien dictionary in the world.
I am an amateur linguist and on some terms with no Tolkien guidance - like the horse's name Asfaloth - I used eclectic interpretive methods, thinking of Tokien's own thinking when he used those phonetic elements. When further Tolkien notes were found and published I pointed out to the official linguists that many of my interpretations were correct.
Their response: I was just lucky.
I decided to move on.
I found it in a Meijers store as a semi-leatherbound ThunderDay Press book. Apparently first text copyrighted in ‘93 and this version is 2016. ISBN is 9781607109068.
Seems it’s a derivative work as there’s also a note that says First published by Mitchell Beazley a division of Octopus Publishing Group as “A Guide to Tolkien” and that some or all originally appeared in “A-Z of Tolkien”, “The Tolkien Bestiary”, and/or “The Tolkien Encyclopedia” also by Octopus Publishing 1979, 1991, 1993.