I have no clue if this will work. Cross your fingers in hopes the two games are similar enough.
- Install, play, and make a save on the USA region Miitopia. (I've never played Miitopia, so dunno how its save system works).
- Install Checkpoint and backup the saves and extdata for both regions of the game. Press (X) to switch to extdata mode.
- Look in the /3ds/Checkpoint/ directory. Within the extdata and saves folders, find the subfolders for your two Miitopias.
- Rename the PAL files to match the USA ones and swap + replace them over.
- Go back to Checkpoint and try restoring your USA Miitopia.
So I tried this out and all the files in the saves of both versions are named identically and are the same size and everything. I'm starting to think that I can just put the PAL save in the NTSC one its just an issue with JKSM as it wouldn't even let me backup the NTSC save whereas checkpoint does let me back up the NTSC save. So now I'm going to see if I can use checkpoint to put the PAL save in or just reinstall JKSM, thank you for showing me this though.
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So I tried this out and all the files in the saves of both versions are named identically and are the same size and everything. I'm starting to think that I can just put the PAL save in the NTSC one its just an issue with JKSM as it wouldn't even let me backup the NTSC save whereas checkpoint does let me back up the NTSC save. So now I'm going to see if I can use checkpoint to put the PAL save in or just reinstall JKSM, thank you for showing me this though.
Ah, so it seems my theory was correct! It was an issue with JKSM reading Miitopia. I'll leave my solution here jic anyone else has this issue. So what you want to do is 1. backup PAL game using JKSM and delete it and install the US version 2. use checkpoint to backup US game 3. delete the files in the US save folder and replace them with the PAL ones 4. use checkpoint to restore the US folder with the PAL save inside and viola!