Alright, I've had a chance to try the latest recommendations from Supernova and... SUCCESS!
It did require me to download the x64 folder and run that .bat file to register the securom driver, which I then put in the correct folder as indicated. When running the game as administrator (without locale software but WITH my Windows 10 administration locale set to Japanese) it worked like a charm. I went back to the debug.ini and tried running the game with the "MovieSkip = 1" part removed, just to see if it worked, and I'm happy to report that it still works fine. The intro movie played without issue, and the game seemed to carry on into the beginning levels.
Now that we have a working process to get this up and running, would it be possible for us to update the files on the Legends site with these updated versions and a write-up about the install procedure that now works? I'd hate for these updated discoveries to not be documented for others that might also want to check this out. I'd be happy to do the documentation if you guys would check it over?
Now that I have a copy that can run on Windows 10, I can start the REAL project: seeing if a fan-made translation is feasible. Do you guys happen to know if anyone has attempted that or if any work has been done on it? You've been around here longer, maybe you've heard something?