I dunno how much was patched. The one im using has english texts, so a translation patch has been applied for certain.
I also had black screens, but then I turned off sound, vblank and put it on full speed speedhack. Reseted from there and it booted up fine. But don't change the settings yet, or it will crash in the menu when you try to start. As soon as you get to the actual playscreen, you're free to change whatever settings you want (sound,vblank etc) and the game will run great.
I've completed the first 4 dungeons so far without any crashes.