You sound so entitled with that comment.
This guy spent his free time making this tool and decided to release it to help us...
Be a little more thankful, he doesn't owe you anything.
----------
UPDATE
----------
Figured it out!
00001131 = EUR
00001132 = USA
ext0 = Slot 0
ext1 = Slot 1
EUR -> USA:
Decrypt your EUR save with SaveDataFiler
Start a new save on the USA version of the game and decrypt this as-well
Move
"SDcard:\filer\ExtData\XXXXXX\00001131\fl_ext0.fsd"...