I installed IronFall 2 days ago, using the old eShop and it worked first try! It took a while to download, but I now have IronHax working on my 10.3 O3DS I got after IronFall was removed off the eShop :P
Did you use the eShop or the Old eShop in homebrew launcher?
If its not working and you use a custom launcher (like grid launcher) use smea's default launcher.
The Japan eShop will NEVER in a million years work on userland (ninjhax2.x).
It could happen with kernel access but I don't think you have kernel access
If you had kernel access you could just install the CIA of that anyway :P
He said he's on 10.3.
Just get Ninjhax or OOTHAX using a save dongle, or hope for browserhax 2.0 or another exploit.
Lots of other people are in the same boat as you, so just wait and eventually a new exploit will come out. probably