The list your linked is from 2012. In the last 9 years ECMA-402 has been heavily influenced by Mozilla's projects like Firefox OS and MozIntl APIs. :)
Unless the specification has been rewritten under another name, I'm not sure why the date matters? The specification was mostly written by non-mozillians and I still don't quite get the point from m0llusk. Firefox OS and MozIntl APIs is not mentioned nor linked in the submission either. Maybe I'm just missing both of your points entirely, if so, I'm sorry.
There have been 9 revisions of ECMA-402 since 2012. We are, in fact, following TC-39 on a yearly cadence of releases.
You can see the history of editions here: https://www.ecma-international.org/publications-and-standard...
The first edition (finished in 2012), had just NumberFormat, Collator and basic DateTimeFormat.
Since then, we added Locale, PluralRules, ListFormat, RelativeTimeFormat, DisplayNames, two new revisions of NumberFormat, two major additions to DateTimeFormat, and we're now adding Segmenter, LocaleInfo, CalendarInfo and working on MessageFormat 2.0.
Here's a very incomplete list of finished proposals that have been merged into the standard and implemented in browsers - https://github.com/tc39/proposals/blob/master/ecma402/finish...
I may or may not be involved in majority of them! :)