I followed your instructions and changed the file settings accordingly. I changed the TextureMipBias in all the files you mentioned from -1 to 0. I really noticed some difference, not huge but the overall image became more clear, smoother and nicer. I also turned on 16x Anisotropy Filtering in my Nvidia Control Panel for Witcher 3. But after that my FPS began to seriously drop. In some locations it drops to 20 and lower. Usually my fps is from 40 to 50. FPS used to be stable. That's maybe due to my videocard's memory - it's 2GB. So I turned the Anisotropy x16 off and FPS count is now recovered and stable and doesn't drop any more. Anyway I see some aliasing on different objects, armor and so on, but its now much better than before. Thanks.Yeah, after a close look I noticed some texture shimmering, also with vanilla textures but it's caused by negative textures mipbias.
However, I found a simple solution to this problem: go to all config files ("rendering" files from bin/config/base and bin/config/r4game/user_config_matrix/pc and user.settings from My Documents/The Witcher 3) and change "TextureMipBias" from -1 to 0. Also for better textures quality I recommended to force high quality and x16 Anisotropy Filtering in NVIDIA Control Panel for witcher3.exe (and the same for AMD GPUs).
After this, textures will no longer be shimmering and everything will be smooth and beautiful.