I honestly find the term "tribal fusion" to be completely confusing-- which is sad because I sort of perform it!
It makes sense to me to call all types of group improv inspired by ATS "Tribal". It makes sense to me to even go further back and call stuff inspired by, say, Bal Anat "Tribal" (although other people would use the term "ethnic", I think a lot of that stuff was made up and so "tribal" describes it better to me).
So, to me, choreo is OK, but it has to at least resemble something that's come from these sources (and not just in costuming) in order to be considered "tribal".
In some ways it also makes sense to me to call something "tribal fusion" when you can clearly identify the "tribalness" and the other element the dancer(s) is/are fusing (like perhaps another form of bellydance or world dance). But if you can't see the "tribal" element, isn't it just "fusion"?
I have taken to calling everything I do as a soloist "fusion" rather than "tribal fusion" because, while I stick to an ATS-esque movement vocabulary while doing group improv, when I do solos I use way too much stuff from my other bellydance background- Egyptian and American Cabaret, mostly- and I don't feel like it's "tribal" any more. (not that this matters outside my little world in central North Carolina!)
I feel like the term "tribal fusion" is frequently both misused and misleading, basically, and I'd have a really hard time pinning down a definition...