Most of what you are experiencing is more than likely the main window font color that is also used throughout windows over dialog backgrounds ( Buttonface color ) In this theme the buttonface appears to be dark green, Black of course will be hard to read over it.
Now this font can be changed to something lighter.. like white or light green or orange BUT then you wont be able to see fonts over your white window background color as it uses the same font color.
This color can be adjusted in Skinstudio in Classic Colors > Window > Text - Normal.
The only solution is to change your window color to the same as that main green buttonface color.. OR change your buttonface color to something lighter that black will be easier to read over. Of course you will most likely have to recolor your toolbar and menu images in a GFX editor to match the new buttonface color.
Welcome to the double edge sword that is...Windows.
