About [[MediaWiki:Massmessage-summary-removemulti/en]]
Shouldn't this use {{Plural:$1|page|pages}}.
This also applies to Massmessage-summary-addmulti ("Added $1 {{PLURAL:$1|page|pages}}
"). If these messages only kick in when 1+ pages are added/deleted then documentation should say this (and it might still be pedagogic to add the singular case in English)
This message is only ever used if $1 is at least 2. The message documentation doesn't explicitly document the possible values of $1, but it does say that it's for removing multiple target pages (same goes for addmulti).
For example, Russian language have multiple plural forms. e.g. MediaWiki:Createacct-benefit-body2/ru.
So singular part should exist to make translation easier.
Made documentation more explicit and submitted a patch.
For the sake of transparance the first account (Skärminspelning) is also me, but whilst doing a screencast.