So let me get this clear, you consider Civil, an overflow tribe, to be a "Shadow" tribe, when it's literally just a sister tribe to store members.
If I am understanding this correctly when you use that term you're talking about unknown tribes that the players are apart of, in this case, Wasted are in - without the Wasted tag.
I'm not sure I agree with this fitting that definition precisely. It's just a sister tribe for over-flow. Yes they have a "Shadow" tribe, but Civil would hardly be part of that - No they're in a ton of other tribes that people don't know about necessarily. However, Civil is known. If it's a shadow it's a shadow that has been cast away and made visible by light.