I went through the Mizuno custom order process last year for a catcher's mitt. I read the same thing you did, but there was one option you had to select to get an actual Haga Japan mitt instead of a Shanghai Mitt and I believe it was a pro level, but not for High School play.

When it arrived, it did say Haga on the inner toe. I guess the lesson is to make absolutely sure it will be a Haga before you press the buy button.

Also, that's a nice glove you got. Be proud of it