i think it's related to the mipmap texture filtering. In this line:
1 ; [MAIN VIEW] Texture filter quality for mipmaps - if any - (0 => none, 1 => point, 2 => bilinear, 3 => anisotropic, 4 => flatcubic/quincunx, 5 => gaussiancubic) v3
if you set the the mipmap filtering to e.g. highest setting 5, you can sharpen the mipmaps then again if you choose the mipmap bias setting 8