in this case the OP already has a 3ds on 9.2 since he's running rxtools though...irrelevant either way since he said he was doing it for his sister's o3dsI probably didn't explained properly:
If you are on a New3DS above FW 9.2, you still have to downgrade to 9.2, to do the OTPless A9LH install.
That is the downgrade I was refering to. NOT the 2.1.
And, as hacking goes, it is the downgrade that has all the risk (either 2.1 CTR-transfer or 9.2 clean downgrade)
In here, you just confirm what I said,