sounds like an electronic attempt at a harpsichord/clavichord. I'd maybe start with a clavinet emulation and adjust the tonal qualities so that is more brittle
each note is sustained for about a beat which is why it seems that it is a cascade of sound - it is playing a continuous arpeggio starting on the root going to the minor 3rd above back to the root then down a 4th and continuing in similar vein - e.g. C-Eb-C-G etc....