About [[MediaWiki:Articlefeedback-form-panel-helpimprove/en]]
This message should use translatewiki.net.
I'm not really sure what message this is; I assume it's a legacy message that has been removed (it definitely does not seem to exist now)
It's from ArticleFeedback, not from ArticleFeedbackv5. The extension has also been disabled completely on Wikimedia wikis, and is considered to no longer be supported. I'll disable translation.
Patch in Gerrit: gerrit:56907.