hello just downgrader my 3rd new 3ds xl successfully now it was interestin the first on which is MMLE downgraded right away no issues from 10.3 to 9.2
The second one which is black was on 9.9 that one got an error message during the downgrade and had to reboot, the 3ds booted to home menu but certain things wouldent work so i used sky3ds and updated to 9.4 and then i successfully downgraded to 9.2.
Now finally the red 3DS i just did was also on 9.9 and i used all the same files on all of them and it did the exact sama thing the black one did,and again i used sky 3ds updated to 9.4 and then it worked. I think the firmware u r downgrading from has an impact on the success rate.