look into the ROM
all text is encoded in unicode UTF 16 LE. (codepage 1200)
uses 2 NFTR fonts, one for the story (lz ompressed, but it seems to use the flag 11 compression again) and another one that is not compressed.
There were few text files, but very small.
Also, more text found in mgentry/text and lgame/txtwnd
There were 2 files ja/wifitext.bin and jc/wifitext.bin that were both encoded in unicode UTF 8.
So basically, because it uses an NFTR font and easily editable text, (even though the texts are scattered), it doesn't seem to hard. The font (font.NFTR)'s size is 10x10, and has single byte characters. The english character's widths are already fine, so no need for a VWF unless you really want a font change.
But I'm not able to view the other font, because of the flag 11 compression.
But graphics will get annoying- all the graphics (NCGR/etc) are all compressed with lz77.
Luckily, the card related stuff are flag 10 as I thought.
The arm9.bin was compressed, but no text in it.
So what I THINK is that the text files are not compressed, and can be edited easily. Card graphics are editable, but I don't know how to decompress the files with the flag 11, so I don't have anything to say about that.