mmmm usually for dvd backups, we need cios/ios 37 to make the instruments work, as the later cios36 doesn't have it and the backup loaders use 36 when loading games.
For me, I use softchip loader and make it use 37 to have the instruments work properly. Are you able to change bootup options with usb loader? (I don't use it

)
Either that or maybe burn it to dvd and play it the above way. I just don't know how pal instruments on a NTSC wii will go.
My pal wii and pal instruments work ok with RB2 ntsc.
Guess its a bit of trial and error.