Hmm, I'm not entirely sure what you mean by "PSX MIDI synth"? All aural duties of the console are peformed by the SPU, you can read about its specifications here.
As far as the samples go, I'd be leaning towards the SC-55. The Goblin sound effect is 100% the same, I agree. Harpsichords sounds similar too. What puts me off is that the overall result sounds "less sharp" than what you would hear as MIDI playback from the SC-55. This could be due to compressed samples or SPU effects. Also, I've never heard choirs that sound like this on any Roland hardware. It could be very well that they used the SC-55 for everything, but they sure must have tweaked the hell out of it.