I think the way Toussaint looks right now is perfect ... why they didn't left the colors like in the Cinematic trailer? Well, because in that trailer Toussaint didn't looked like it was described in the books and the second reason is, if you gonna make a new area for a large expansion like B&W is, you want to make that area different and unique in comparison to the other areas..
Velen looks different than Skellige, Skellige looks different than Kaer Morhen, KM looks different than those two areas, Novigrad looks different than all of them, etc.. so naturally Toussaint should look different than all other areas.. CD Projekt RED just followed the descriptions from the books.. and Toussaint in fact is the best designed area in the whole game + pretty much everything in that area is better designed then anything in Velen/Skellige/KM, because the new are doesn't have basically no filler.. and the writing is still miles better than in the majority of modern games.. yeah, the main story sn't as strong as in HoS or the main game, but in my opinion the main story has one of the best scenes in the whole trilogy - the table scene between all the major B&W characters.. similar scene was really missing in the main game between Eredin and Geralt, Ciri or Avallach.. + the side quests were all still very high quality + they nailed the character of Regis - maybe the best transfer of a character from to books to games in the Witcher trilogy
Anyway, you are doing a great work Essenthy with the game and I'm really looking for the new version of the mod..take your time of course with that