I too found the notion of metaphor compelling.
"Gaps develop in the seams of universal projects; they are found where universals have not been successful in setting all the terms"(202).
Tsing goes on to note that "whenever we want to trace the limits of hegemony, we need to look for gaps," as "an ethnography of global connection is impossible without this tool."
I consider here her use of the word 'connection' and find it indicative of the encounters (as opposed to representation) of which you write. I agree that misreading Tsing's work as being focused primarily on representation (or even the limits of representation) has destructive and retroproductive potential; as I believe we often situate our examination of global/local/glo(c)al interactions ourselves too rigidly in the two entities set apart from one another rather than setting our investigation in the distance between them.
For there is distance even in friction, as two entities wrenched across one anothers' surfaces do so because they cannot fully consume, erase, or surrogate the other. Of course, their interaction (or encounter) produces another thing all together: a sort of dialectical explosion at the stitches of an ambivalent event.
So, what is productive about hegemony? What is productive about the universal, or, rather, conceptions of universals?
Tsing notes that "the concept of freedom is much abused, and yet the idea of freedom is still as important a tool as any for the disenfranchised"(203). It seems that an empty, useless 'universal concept' / 'universal human right' called freedom is made palpable by the very thing which complicates it: plurality, its myriad meanings in a single moment (thanks to a multiplicitous human population) and its myriad meanings across time (thanks to an evolving human population and the environment(s) working to (re)produce the species).