Also,
here's an .ORG transcription of my favorite Sonic 1 song. I feel as if the instruments I chose could use some work, but I'm just gonna publish this now for some feedback.
There are some minor issues, but overall it is a nice transcription! Mostly accurate note placement, and the choice of instrument of the bass is fitting. The biggest problem for me would be track 6, as it is an octave too high, which kinda hurts my ears. I would lower the whole track by one octave. Also, I think the bass track is one octave lower in the original, but it sounds fine where it is now so that's more a matter of preference. There are some minor things too, like the choice of instrument as you mentioned. I think the square-sounding waves for tracks 3 and 6 work well enough, and I mentioned before the bass is good, but you might wanna try experimenting with the others. Also, I think the song (specifically track 6) would benefit from the volume decay commands. I applied the "decay slow" command to the whole track just to see what it sounded like, and it seemed to sound more like the original than without volume decay, so you might want to examine the original song a bit and determine when the volume drops off for each note.
But those are mostly just minor nitpicks, so good job on the song! I do love Spring Yard myself.