It sounds like that would just play the same sound, only delayed/stacked. The actual sound would need to be... almost like a time stretch if you will? So a short snare with a sharp hit at the beginning would get dragged out so the hit is still only at the beginning, and the trail off of the snare would be greatly extended.
I am using a converter, spc2midi. I have just a small amount of control over what it does. I can select instrument, pitch, enable or disable attack and decay, and adjust volume, chorus, and reverb for each of the 16 "instruments" in this bit of the music. Attack and decay don't affect the percussion it generates.
But thinking about this now, perhaps I can use a non-percussion sound (reverse cymbal or seashore?) and reduce the volume of each step? I'll have to give that a shot and see what happens.
If it doesn't work very well, my last course would be to edit the resulting midi file and manually add some things with a MIDI editor. But that brings me back to the question of it being possible to play different "parts" of a midi sound. Perhaps manually modifying the attack/decay on the subsequent pieces so the sharp hit is not audible?
I'll post the file as-is in a bit after I export it, so you can at least hear what I am talking about. Until then, you can hear the original part I am trying to replicate here:
https://www.zophar.net/music/nintendo-snes-spc/super-turrican
Track 2-2
listen to the repeated cymbal sound at 34 seconds, followed by a snare hit that lasts (I realized it's hard to hear because I was listening is a player that let me mute the other channels). You can hear short versions of the snare sound elsewhere in the track (and better in track 2-1, which also has repeated long and short versions of it), and at 34 seconds the long version. The actual sound is the short one. The longer one is the multi-stack/stretched version.