About [[MediaWiki:Pagetriage-info-timestamp-date-format/en]] and [[MediaWiki:Pagetriage-creation-dateformat/en]]
Fragment of a discussion from Translating talk:MediaWiki
This topic is currently marked as closed. I guess it should still be open, right? If so, please feel free to edit the thread summary.
Looks like my initial assumption that it uses MediaWiki date formatting was wrong, so my suggestions were wrong too.
I already opened a bug about it: Bug 39379 - PageTriage uses custom date formatting.