To support T34189, the interwiki map config (computed in SiteConfig) needs to have the localized message for the interlanguage link prefix. However, this requires us to call wfMessage in SiteConfig which is a tad shady.
Instead of injecting i18n messages in the SiteConfig, we can record the message key in SiteConfig and have Parsoid generate the appropriate i18n info/wrappers for the link which will then get processed like everything else during the l10n pass.
Change 837146 had a related patch set uploaded (by Subramanya Sastry; author: Subramanya Sastry):
[mediawiki/core@master] SiteConfig: Record the localizable message name for Parsoid
Change 837147 had a related patch set uploaded (by Subramanya Sastry; author: Subramanya Sastry):
[mediawiki/services/parsoid@master] WIP: Handle localizable title in (interwiki) language links
Change 837146 merged by jenkins-bot:
[mediawiki/core@master] SiteConfig: Remove commented out dead code
Similar to ToC information, we might need to figure out how to consistently mark those bits of ParserOutput which require processing during the l10n pass.