This is the most minor thing ever, but the manual currently says under stat x

20..23  Note number (0..31) on channel 0..3

...but if the LEN of the SFX or LOOP endpoint of the SFX is greater than 32 and the SFX plays that long, then stat(20..23) will display numbers greater than 32 just fine.

I don't know if this is worth fixing, but something like "(normally 0..31)" would be technically accurate and still probably convey the desired information.