Ah, when you said it was a common problem with the game related to emunand I assumed it was a wiiware title/wad. I'm not sure how this issue would be related to emunand if it's a normal wii game. If it is somehow related to emunand issues then just don't use emunand for this game.
But yeah, maybe u will need to use a usb for this game.
I do have 1 other idea to get it working off SD, but it is complicated, could end up corrupted files, and may not even work. But basically build sneek+di with SD access enabled, if using modmii it's in the settings. Then launch the neek menu, load the game through the di menu / emulated disk channel, and hope for the best.
Because the emunand is on sd, and sd access is enabled, and the game is looking for music on sd, there's a possibility of something Going wrong and corrupting data. Either backup your data or test it on a fresh SD card