Vitali,
Apologies for the delayed response. We missed seeing your post.
I am afraid there are no settings available for tweaking the Terminal+ background or font color. Those colors depend on the theme selected in the workbench.
For a darker background, you can select a dark theme here : Window > Preferences > General > Appearance. If you have installed our Darkest Dark plugin, then select DevStyle theme in the Appearances page and in the DevStyle > Color Themes page, select any Dark theme as Workbench theme. Apply the changes and restart the IDE for the theme to be fully applied.
Hope this helps. Please let us know how it works for you.
–Swapna
Genuitec Support