I have tried in your materials.lua line 23 : MDG_materials[MDG_SELF_IDS.HUD] = {2, 255, 30, 140}
A slightly different green and less intense.
Finally, with your 2.1.1 version I changed it to MDG_materials[MDG_SELF_IDS.HUD] = {2, 255, 25, 150}
Looks perfect for me...