In my experience "pairing" is used colloquially to refer to pair programming and I suggest that this is the presumptive meaning in the context of Emacs.
If a tag is needed to represent automatic closing or matching of parentheses/quotes use something like '[auto-closing]' or '[auto-pairing]' with or without hyphens.
For those curious: [pairing] on SO refers to device pairing.
- Create the tag [pair-programming] (same as on SO; very self-descriptive).
- Alias [pairing] to [pair-programming] (create a tag synonym).
- Remove the tag from the other 3/5 usages.
If there is a solid consensus I will go ahead and do #1 and #3 and request that someone with 2.5k rep do #2.