1. It doesn't show an "original name" - it shows a pokemon type. Unless you're sure the name doesn't say "Jirachi" in japanese, you can't tell it's nicknamed.
2. If it's OT is not japanese, but it's name is, it's a hack. It might have started off being legit and someone hacked it to change the name, but that's just dumb.
3. If you're looking for legit Jirachis, I've got plenty of event jirachis (w/ bad stats) for trade - japanese, english, etc. However, I just Vmed you to give you a heads up, not to go into a sales pitch. :P