[[Osm:Notifier.gpx notification.success.loaded successfully/en]] should use PLURAL
Osm:Notifier.gpx notification.success.loaded successfully/en should use PLURAL
This message should use PLURAL for both parameters.
Ruby plurals are only possible on one parameter in a message. Yay for half-assed i18n frameworks by native English speakers. Please make a bug report in the OpenStreetMap tracker.
That message isn't actually used at the moment, as we don't use the ruby GPX importer and the C one which we do use doesn't use the rails translations.