This was modified long ago in r6670. I would keep it by default in content language since it generally holds a lot of content that would be hard to translate in every language (see e.g. mediawiki.org). As stated in the commit summary you can ask to add it to $wgForceUIMsgAsContentMsg for meta so that it can be translated.

(In reply to comment #1)

..generally holds a lot of content that would be hard to
translate in every language

I have no clue what you mean here.

The default line is:
http://translatewiki.net/wiki/MediaWiki:Recentchangestext/en
"Track the most recent changes to the wiki on this page."
Which is as user-interface as can be, makes no sense to me for this to be in content language as much as it doesn't make sense for the Sidebar, Tabs or Footer to be in the content language.

If some users (WMF) decide to put entire tables, images, headings and links to all sorts of stuff related to editing and counter-vandalism in this message then they can translate it in all languages (like Commons and Meta do).

I'm with Krinkle, this should probably be fixed, but I'd like to know why this change was made in the first place. I've tried to open a discussion with the person who changed the code at r6670.

A solution would be to move the content of this message to recentchanges-summary and we could keep this message with an empty content per default.

Fixed in r86186.

Reverted with r86294 due to bug 28590.

Fixed in https://gerrit.wikimedia.org/r/#/c/6230/

Follow up: Bug 37015.

In T27946#3350330, @Jdforrester-WMF wrote:

This actually didn't get fixed, sadly (see https://mediawiki.org/wiki/Special:RecentChanges?uselang=qqx for instance). It's a bit tricky to fix due to the battling desires for inheritance and over-riding. Will try to work up a patch.

This currently shows two things:

• (recentchanges-summary) - Which means it used the qqx user interface language
• Followed by the local template from [recentchangestext](https://www.mediawiki.org/wiki/MediaWiki:Recentchangestext)

Which means that that is definitely using the content language?

Yes, it is definitely using content language, which is what this task asks to not be the case.

In T27946#3375585, @Catrope wrote:

Yes, it is definitely using content language, which is what this task asks to not be the case.

Aye, right. Tasks titles in the form of a statement are a confusing anti-pattern (he says, to his 2010-self).