Did a little bit of work on Multilingual MediaWiki a long time ago.

Joy of joys, language tag unicode extensions were adopted as a BCP 47 unicode extension.

Sort (numeric) reverse, USD dollars as an American would.

u-cu-usd-u-kb-true en-US-u-tz-uslax
$100 7/22/2011 10:00 pm

aria-sort only labels the primary row being sorted: