Last modified: 2014-04-03 11:40:29 UTC
Lua's mw.language:formatDate shouldn't have the same 6000 characters limit that ParserFunction's #time has, since the Lua scripts are already limited in the duration of script execution and memory consumption. [Forwarding for Paweł Ziemian per https://www.mediawiki.org/wiki/Thread:Extension_talk:Scribunto/Limits_of_mw.language:formatDate .]
This is fixed by Gerrit change #120156, which should be deployed to WMF wikis with 1.23wmf21. See https://www.mediawiki.org/wiki/MediaWiki_1.23/Roadmap for the schedule.