Unfortunately not. After the region verification on the card header there's language verification on the vpk.
0xD26, 0xD3D and 0xD3F
0x01 Japanese
0x02 English
0x03 French
0x04 Italian
0x05 German
0x06 unused
0x07 Spanish
You can actually skip the whole process with pasting the edited vpk back into the card. Just use nedcmake from the dev tools and rebuild it. I guess I should update the guide at some point.
Region 1 = US, 2 = Japan, Type 1 is for berries and trainers.
nedcmake.exe -i card.vpk -o card.raw -type 1 -region 1