One of the nice features of mapfactor (android version) is that you can customize the map scheme's. In the settings - map customisation you can choose different scheme's. Perhaps one of these screens is the right one for you. Bu you can also edit many aspects of a map scheme: global - text - line - area. In the line area you can change the way the roads look.
But be careful. The number of possibilities is huge so it is very easy to make a mess of it. This is what I would do: 1. choose the scheme that you like the most. 2. clone this scheme and rename it to test. 3. experiment in this test scheme.
@hvdwolf is right - there is no way to edit it in album.style (and we are not able to change it, sorry)
@MacDony - anyway I did small modification in 3.1.73+ (it should be on beta this week), I added detection that screen is eink (using hint here: https://stackoverflow.com/questions/15221787 - I am not sure if it will work ok on your device as there is getDefaultDisplay())
Anyway if eink display is detected than width of road borders will increase and centering animation will be disabled (you should not use it with 3D mode)
@Lubos, on the xda forum, some have made applications for the e-ink screen. I thought there would be useful information. . Folder "eink"in "\Android\data\com.mapfactor.navigator\files\navigator" or "navigator" ?
It seems I made mistake in rescaling road borders. It will need a bigger code review and we are already releasing 3.1.92. I will try to fix it in future version.