Person, not people. You're the same guy who PM'd me; I gave you the run-down of it. IIRC the menu text isn't graphical, for the most part. The parts that are graphical are usually decompressed by LZ77. However you also have to take into account the TSA. I suggest GBAGE for these kind of graphical edits. Actually making the graphics is another thing within itself, of course.
If the graphics aren't some standard compression (you can usually tell by looking at the header of the file and possibly the file extension, if you're already familiar with the file extensions the game uses) then that's something different that I'm not experienced with, unfortunately, and you'll have to figure out on your own.
While I'm at it, I've already cracked how to do a dialog translation, with some help. Fixing the issue of certain fonts not working in certain areas is another matter that I've only thought about and haven't cracked because I quit the project. As I said in the PM, if you just check on my website or google "fire emblem DS documentation" you should find a lot of useful info that can be applied to FE12, even if it's FE11 based. Unfortunately my notes on FE12 itself are scrambled and few because I did that patch in a rush and not very professionally (if you couldn't already tell).