The newsletter update states that Visual Editor is now functioning in the content namespaces at MW, which includes the extension: and manual: namespaces (and it does). That said, the default text for "MediaWiki:Visualeditor-preference-enable" just states user and main at that wiki. I am presuming that this is a WikimediaMessages update somewhere
As a temporary measure I have created [[mw:MediaWiki:Visualeditor-preference-enable]] that mentions the extra two namespace.
As a note the mention of {{MediaWiki:Visualeditor-extensionnamespacepagelink}} and {{MediaWiki:Visualeditor-manualnamespacepagelink}} failed, so I didn't link, and we will need to look to how these extra namespaces are going to be linked, and documented.
Version: unspecified
Severity: minor