The original plan, from what I saw in the very first post, was:
'As vivify93 announced in his thread for Project II, he and I decided to allow me to branch off for Namingway Edition. For those looking now, this is my attempt at at taking Project II and renaming the items, spells, and monsters to a more traditional naming, and matching, if possible, the names used in modern releases of Final Fantasy IV. '
In other words, he'd originally planned to just adapt Project II and use Japanese names to match modern releases.
That he started adding things -from- the original Japanese is pretty much him deciding to try and expand from this base.
So this is basically an continuing development of Project II based around expanding it to 'Japanese extras'.
There's a reason this is a 'hack', and not a 'translation'.
If you want to make it -exactly- like the Japanese, I think, you want it to be a -translation- of the original Japanese rom, not a hack of the US Rom.