Hey, patch team member of FMW:E here.
I was busy during the starting period of this (although I still managed to scrounge up enough time to blast through the game and provide some translated lists for it) so I didn't really get involved, but I'm glad to see it's working out of sorts. I was mostly a translator and image editor for FMW:E, so I'm not entirely familiar with the tools used to extract the scripts from the .dat files, but I'll try to provide some insight on the hacking process and potential pitfalls based on what I know:
-I see that fishcicle found out that this is a Gamemaker 8.1 creation and (I presume) found a decompiler for it to extract the source code. Just as a precaution, I've tried this before and had problems recompiling a workable exe after making minor changes to the source code due to missing libraries/dlls; I'm not sure if you (fishcicle) have managed to solve this, but I'll just throw it out there if it hasn't been tried yet.
-For the extraction of the dat files, I believe the hacker performed this by finding the routine that read the text files from the .dats in the game's source code, then re-coding that portion to dump the text files that were read into another folder on the hard drive, and creating an executable from the new source code. This circumvented the encryption of the .dat files entirely. I presume something similar can be done for this as well. However, I'm not sure how repacking into a .dat file was done, but I would guess that if there's a way to read from .dat files, there's a way in the source code to write to them as well.
-If the format is anything like in FMWE, then a rough menu patch can already be done based entirely on translating the Japanese strings found in the game executable. In FMWE, most of the important menus and images could be found in the exe itself; the dat files contained most of the game's dialogue, including intermission, mission and battle dialogue, and included some images of certain menus.
-From what I've seen, there isn't an image editor on board yet; I would suggest getting one quickly, or at least once work starts in earnest, as some important menus (such as the status screen) are actually entirely images for the non-variable portions, as well as other important things like the commands themselves (Move/Attack/etc). I wasn't particularly satisfied with the job I did in FMWE, so I hope someone who's better at it can take up the baton here.
-I'm rather busy still after a 9 month hiatus or so, but I'm also willing to help in translation if it is required. Though it seems there's enough manpower on that end, so I'll just focus what time I do have on DoD if that's the case. (Though that's what I said during GoS/FMWE too, and look how that ended up...)