Your sysnand is unlinked from emunand. You won't be able to play it on your sysnand because you would have to update it before it will let you use eShop or relink it to an NNID that bought the game.
I would have had told you just to flash emunand to your sysnand, but you already have it updated to 9.4, so obviously that would be a bad idea. About the only thing you can do is boot into gateway mode without emunand and install a CIA of the game to sysnand. Issue is, you won't be able to play it without being in gateway mode. So you're out of options unless you have a 9.2 or older emunand that you backed up that still uses the same NNID as your emunand. At which point you can just flash that back to your sysnand via the downgrade menu.
Yeah he could relink nand by flashing a 9.2 or older version of his emunand to sysnand. That's if he backed it up before he updated it to 9.4. Otherwise he'll have to format sysnand and recopy it to emunand.
Not sure why you'd want them relinked though. Issues arise from doing so. Like having to unwrap games/homebrew installed via DevMenu/BigBlueMenu/BigRedMenu and not being able to organize the icons (they would constantly reset due to interaction with sysnand)