text: I'd start by commenting on changeset discussions.  The nodes are in Scotland, so using English would seem reasonable (Gaelic is a bit less international...).  If no reply, drop a mail to data@osmfoundation.org .  We can send a message that needs to be read before they continue editing.  If that doesn't work, we can block for longer.
  Until any contact with the user has been made they'll be blissfully unaware of any problems.
  Best Regards,
  Andy Townsend (SomeoneElse) on behalf of OSM's Data Working Group.