Hello, (sorry for my bad english, I use google translator)
I participe to the French translation of Miku Extend (and I am the author of the French translation of Project DIVA 2nd), and recently I changed the font for menu of the game to add accents "é" "è" "à" "ê ", if ever other translators want to use it, here is the file: http://img600.imageshack.us/img600/89/font12dot01.png
(I replaced some Japanese characters (taking a single byte) as follows:
ｪ = é
ｫ = è
ｬ = à
ｭ = ê
If other translators need to add characters into the font of the game, I have some explanations to avoid this: http://img210.imageshack.us/img210/921/pic0026.png
or this http://img444.imageshack.us/img444/5571/pic0030.png
I have not changed the font of PV, but it happens anyway, if we do not do certain things:
The game uses the color palette information from font12dot_01.png, and does not check the colors informations from font01.png (so the game use the palette from font12dot_01.png again).
The problem is that often when we modify the PNG with Paint.NET or any other software, it changes the palette, and thus the display of other fonts.
So a few tips:
posterize your font12dot_01.png modified (to reduce the number of color).
use "OptiPNG" ( http://optipng.sourceforge.net/
) or "PNGOUT" ( http://advsys.net/ken/utils.htm
) to save your file by taking the least amount of space (pngout is more effective).
Use "TweakPNG" ( http://entropymine.com/jason/tweakpng/
) (Open two TweakPNG window, one with the original png, the other with your edited png) to make your file much closer to the original. (edit the header, split the "IDAT" and especially edit palette and alpha to make it identical to the original).
By the way, the last two values color / alpha of the palette match the background behind the characters and the color of the letters themselves.
I hope these explanations will help some translators