Here's my best guess:
a: click with a slight rattle, like rattan brushes
b: closed hihat
c: distored synth bass with rattle, like tambourine
d: distored synth bass higher pitch and muted
e: muted synth bass
f: sizzle ride hit like crash
g: maracas
h: muted maracas
i: afuche-cabasa
j: synth snare
k: deeper snare
l: castanets
m/n: tap on closed hihat - maybe striking the hardware?
o: booming tonal bass
p: half muted tonal bass
q: muted bass
r: very muted, blockish bass
s: synth splash
t: agogo bell
u: guiro upstroke
v: guiro downstroke
w: tamborine
x: snare
y: synth snare
z: concert bass
non-alpha: rest
(): beat = 1/3 - note: triplets will begin on the letter before the first open paren, it modifies the space before, not after, each note.