Nice find! I love this soundtrack with a passion too and would also like to know more of the pieces that inspired it. No idea how much of the soundtrack is completely original, but I'm sure there are more tracks adapted from or inspired by some piece of classical music.

Not entirely sure if it's an adaptation, but I heard distinct similarities between parts of Court Dance and the final movement of Dance Suite No 3 from the 17th century Banchetto Musicale.

Court Dance:
https://www.youtube.com/watch?v=5do1rt_qeIw

Three suites from Banchetto Musicale (LP):
https://www.youtube.com/watch?v=ADxunZfkvT0
The part of interest is Suite No 3 in A major: Allemande - Tripla, which plays from 21:35 to the end of the video.

I know the soundtrack was made by German composers/musicians Joachim Schäfer (not to be confused with the trumpeter) and Gerd Hofmann. The former has an official website and email address (joachimschaefer.com), but I have no idea whether he accepts messages in English, or would be willing to say something about this at all (or even remembers the game, heh).