Especially with bug 70850, it is very hard to keep track of global renames. Thus, I believe it should be considered to leave a local log entry on Special:Log/renameuser each time a global rename affects the wiki, for convenience of the local users.
Currently, the only local log entry is left in Special:Log/move, but only in case the renamed user had a user page on that particular wiki. I believe users without a userpage should not be put at a disadvantage and as well get at least one log entry.
Version: unspecified
Severity: enhancement