I too noticed that some small shrub is too light (translucency too high). Good idea to make the colors more vibrant, sometimes tundra's are quite red/orange. I'm always a bit (too) careful about color.
The railway's width is exactly 143.5 cm, I measured it all out, even rail and sleeper widths and heights, etc.
I was thinking of adding a small station on an 'island' in the middle of the largest lake, plus a landing and a boat and maybe some more stuff to add a little story to this......