Okay, I tried it out and they did not revert to their Katakana names. I guess I'll have to give them Katakana "nicknames." :frown:
EDIT:
This means that yes, I would still like to get the PKM files.
I am in need of Japanese, non-nicknamed .pkm files of the following Legendary Pokemon from HeartGold:
Raikou
Entei
Suicune
Ho-Oh
I forgot to switch my English-patched Japanese game back to the original when I caught these four.