The chapter about Trollworld in the Deluxe edition of the new T&T rulebook was the result of a compromise. The Fellowship of the Troll had so much to do that it was impossible for them to produce a whole book about Trollworld. However, the material available is much more than 100 pages. It is more like 300 pages. It was "just" a matter of gathering the material, structuring it, correcting the errors and inconsistencies, and… of translating it into French. I have been working on this since 2012 and... It is now my pleasure to give you Le livre de la Terre des Trolls!
I will have to disappoint you, mahrundl, but no English version is planned. However, I gave Ken, Steve, Bear, and Liz access to the material I gathered to make the book, and to the very first draft in English - as it was - at first - only a matter of assembling texts written by Ken and his co-authors, including Mike Stackpole. Over the years, I had to make a lot of very small corrections and additions. Sometimes, I had to use different versions of the same text, and to pick up and choose the best parts. I had to assemble texts that were not formally connected to eachother, etc. There is a point, a few years ago, when I stopped to update the English version and when I chose to work directly on the French version, based on the different sources I had in English. That saved me a lot of time, but of course, that does not help the English version! If I were to re-construct an English version based on the French book and on the original material in English, that would take me hours of work. So, it is now up to Ken and Flying Buffalo to see what they want to do. They could use the material I gathered for them, have a look at the French book, and start to write their own book on Trollworld. And they could also get a licence from Simon Lee Tranter to use his artwork. In fact, they could make a better book than me, provided they invest a lot of time and a little money.
Congratulations , looks amazing. I hope that the Fellowship of the Troll will seize the opportunity to use what you and Simon Lee Tranter have created to do an English version but it is wonderful that there is so much support for T&T in France.