I don't know in this specific case, but generally if you license something all things you create for that license are usually the property of the license owner. XSEED licensed Falcom's games and are translating them, therefore Falcom probably owns their translation. IIRC XSEED's script for HMH was used for the XBLA game, as well as Acquire's self published iOS ports of Wizardry. XSEED had nothing to do with either release.
That's not how it works, as far as I know. XSEED most likely licensed their translation out in both of those cases. It seems impossible for them to get no credit nor cut from their own translation work.
Okay? You use NPD data to get a good grasp of the sales of the game. If HMH sold 1200 copies in the NPD report I don't think Aksys will suddenly think 10,000 must've been sold on PSN and Wal-Mart. Especially given Aksys had actually released PSP PSN exclusive titles and have seen their sales potential first hand.
Edit: Just before anyone freaks out, I don't know HMH's sales. The stuff in my post are just made up numbers.
I'm just correcting your assumption than NPD somehow is the final word on sales. It's a decent approximation, but not the total number. I never played Jikandia, but it looks like it required next to zero localization - even less than HMH.