DLed and installed RX9 and I'm having the exact same problem.
Starting the game with either InitSetting or just the Koikatsu application leaves me staring at a bunch of Japanese characters.
I didn't bother trying to see if any of the other mods or features worked because it is, unfortunately, unreadable.
Like I said before, no clue why this started happening. One night I closed the game and the next day when I opened it up it just refused to see anything but a vanilla Japanese version.
At this point it's really more trouble than it's worth. Unless someone else had a similar problem and found a simple fix I think I'm going to write this game off.
Keeping in mind that I'm pretty computer illiterate so a complicated solution is probably going to go right over my head
I appreciate your suggestion though. Thank you for that and have a great day!