In a recent post, Dr. Leiman noted that Rabbi Dr. Dovid Tzvi Hoffmann's commentary on Shemot is being translated into Hebrew and printed in the near future.  While the volume on Shemot will be published, a commentary of one of R. Hoffmann's student on Koheles has recently been translated and printed.  Indeed,  there are two editions of the same commentary that have been recently been printed.  The fact that someone who has been ignored for a while then merits to have competing editions of their work is not that uncommon. For example, recently, there has been a renewed interest in the works of the Aderet.  The Adret's commentary on teffilah, Tefilat Dovid, there are three editions when five years ago there were none.

In this case, there are two editions, one in Hebrew and one in English of Dr. Gerson Lange's commentary on Kohelet.  The English edition titled, "The Book of Koheleth," is edited by Yosef Binyamin Fagin and includes a short biography about Dr. Lange. A slightly different version of this biography was printed in volume two of Yeruhaseinu (English section, pp. 22-31). Dr. Lange was a student of Rabbis Hoffmann and Hildesheimer and eventually took over as Director, after the death of R. Dr. Mendel Hirsch of the Israelitischen Religionsgessellschaft Realschule in Frankfort.  In this role as teacher, Dr. Lange taught Kohelet to his students, this work is a product of those classes. 

This is not Dr. Lange's only book, he also translated the Ralbag's Ma'asei Choseiv, a work on mathematics.  Dr. Lange, after obtaining semikh, studied mathematics at the University of Berlin.  In his commentary on Koheleth, he makes use of his mathematical background and even discusses Newton's Theory of Emission in the introduction.The commentary is one of peshat and many times focuses on eytomology to find the peshet.  The English version produces a highly readable translation. 

The Hebrew version, titled Gerash Yerachim, although the original title was, as the English version renders it, The Book of Koheleth, the editor decided to come up with a new title – a point that is not mentioned anywhere in this version. Additionally, this version, according to the editor, is not a translation but adapts Dr. Lange's commentary.  This version contains an introduction and background on Dr. Lange.  The introduction appears to take on a more apologetic tone than the English version.  Specifically, when discussing Dr. Lange the introduction points out that although Dr. Lange went to university buty that "going to university was common amongst the German Jews and without obtaining an advanced degree they could not function in any communal role, even amongst the Orthodox communities . . . [Dr. Lange] was following in the footsteps of his teachers, Rav Ezreil Hedesheimer and R. Dovid Tzvi Hoffmann and going up in holiness the Goan R. [Yaakov] Ettlinger."  Additionally, the introduction goes on to recount how R. Meir Shapira visited a resort near Frankfort, "Dr. Lange would get up at four a.m. and go to R. Shapira to study with him.  When R. Meir [Shapira] came back into Frankfort he proclaimed 'A Jew like [Dr. Lange] shows that there are still beni aliyah amongst the German Jews!'" Whether or not this tone was the intent of the editor, is of course, difficult to discern but worth noting. Finally, a short review of the Hebrew edition appeared in volume three of Yeruhaseinu pp. 399-400.

Both of these versions should be available in your local seforim stores, or the English can be purchased by contacting langebook-at-aol.com