My personal experience:
1.- I used Julian20's (SULib) one to downgrade and it NATIVE_FIRM AT THE END of the installation every single time! with 3x 9.5 FW consoles which failed mid-downgrade -> "softbrick" -> "boot without the sdCard, insert it once booted again to sysNand" -> enter via browserhax -> run sysUpdater and Downgrade again...... finishing the downgrade without a problem after that and as I said.. NATIVE_FIRM after installing the files at the end.
2.- I used one that deleted NATIVE_FIRM AT THE BEGINNING of the processs (this one lead to a softbrick which only left me recovery mode to get the console to work again... lucky me at that time the newer firmware version was 10.3 so no probs) <-- this one was downloaded from a "downgrade pack" from a youtube video tutorial I followed before finding this wonderful forum, this one was on 10.3 (first console I tried to downgrade ever).
3.- I used safeSysUpdater and it installed NATIVE_FIRM IN THE MIDDLE of the installation...... 10.1 downgraded without a hassle....
4.- I used safeSysupdater with a 9.9 Firmware N3DS and it failed miserably and ended in Frankenfirmware used OoT3D entrypoint and resumed with Julian's SysUpdater (SULib one).
4.- I had another 9.5 console I just downgraded like 10 minutes ago xD which used safeSysUpdater it failed after it NATIVE_FIRM IN THE MIDDLE OF THE INSTALLATION and it ended up in Frankenfirmware... used OoT3D as entrypoint.... resumed downgrade again with safeSysUpdater.... downgraded without a hassle after that =)
so... that's my story xD
Which version did you choose when you use oot3dHax to insert a savefile,, 9.9 or 9.2?