To be perfectly honest, the majority of these translation projects is little more than coding. Writing in a variable width font, doing any necessary changes to allow longer strings, message width formatting, text bank extensions, codec work, that sort of thing.
Once text is extracted you'll probably be able to find some very kind, generous, or at the very least vaive person to translate the script. Of course I'm being a bit sarcastic, but I've been hooked into projects more than once just because somebody asked very, very nicely and it seemed so much simpler at the time ;*)
Funny enough, did make a decompressor but can't verify the output. That might seem odd, but I have a good reason to believe that Nemu64 cuts off the last byte of each 0x400 segment read in by the decompression routine, leaving it zero. Reason being my extracted images so far haven't been horribly corrupted; and my output is the same size as the header's decompressed size, whereas Nemu's is much more if byte 0x3FF is ever a command byte.