>>33887330a japanese 3ds will play japanese games, so yes you can get it early and then get japanese events
however most japanese events are either in person or via code you get in person, so it's kinda useless if you're not physically there
besides you can just change your 3ds region if you hack it to go japanese if you ever need to and then change back
as for using the early save file, you can use wifi once the actual release date hits, just not before, so you would get to play 10 days early and start wifi the same day as you would if you didn't get to play the offline 10 days early
literally no reason not to do it
