How did you update to 9.2 u though? I try using the 9.2 files from the iso site and devmenu to install them, but the firmware of the emunand wont go past 9.1 j. Will the video explain it?
just installing the system files wont do. you also need your xorpad dump of your emunand, which you can get through decrypt9. you need to inject a file called secureinfo_a into your dump, which is where the region changing happens, and then use emunand tool to combine it all back together into your 3ds. the system files are all it is, just files, it doesnt change the region of your console itself yet.
after doing all those you need to remove old japanese system files. its all covered in the video.
Basically in layman's terms what you're doing is
1. Start with a Japanese 9.1J Emunand
2. Extract your Emunand with Decrypt9 (Xorpad dump) into a file and put this in your PC
3. Install US 9.2U system files to 3DS, and take your SD to your PC
4. Go to your PC, inject USA version of Secureinfo_A into your file (Xorpad) you extract earlier (This changes your region and language to USA)
5. Inject this new Xorpad into your SD on your PC
6. Load up Emunand, you should now see English menus and be in 9.2U or whatever version of files you used
7. While in Emunand, go to System Settings and format system
8. Lastly, use FBI to delete old duplicate Japanese system files from your system.