From https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Globalrenamerequest/en:

If I remember correctly, this form was introduced during the last steps of SUL finalization on Wikimedia wikis, to help users whose account had to be renamed before it could be SULified. But all accounts are now global, so "Unification rename request" is confusing. Could it be changed to something like "User account rename request"? Or "Global user account rename request", if the clarification is useful for non-Wikimedia wikis?

I personally like the latter suggestion.