AFAIK (and I've just checked) that 3ds key site doesn't have the keys to the base game of Project X Zone 2 yet (searched using the title ID from the Euro - 0004000000162000 and USA - 0004000000160C00 versions).
What it actually have is the Key for it's DLC, and they are kinda of useless because:
1 - They are only bonuses items for the game, you can get them with NTR or Gateway cheat system
2 - They are actually validated, you can only use their effects after you download them using the in game interface because only after downloading said DLC the game will patch the save to put said items, force installing the DLCs using FBI didn't achieve their effects in my tests.
Suggestion that I've made on freeShop thread and will repeat here, if possible add the option to download updates and DLC for games that doesn't have their keys for the base game on that key sites or own dumped keys. The Project X Zone 2 is a good example, people have it's CIA made with dumps from cartridges (heck, I've dumped my own game because I wanted to carry less game holding cases with me), but it have updates and DLC (even if useless).
The freeShop have a routine where it shows in the installed game list retail cartridges, but it only shows games for whom you have keys (so Project X Zone 2 doesn't get listed, but any game that you can download today using freeShop get listed when you insert the cart).
My suggestion is to add a routine to show DLC and Updates to said cartridges (and CIAs) I know that people can use FBI, CIAAngel and other methods to get these contents, but it would be nice to see it added to freeShop.