I noticed how World.ini actually takes in the names of the sound effects for shifts (ShiftSound(A)=Electronic rather than something like ShiftSound(A)=2), and in wishful thinking I hoped that this was a sign that Knytt Stories implemented a way to have custom shift sounds.
So I took two files named CuicaMute.ogg and CuicaOpen.ogg and tried many things. I tried putting them in the root of the level's folder. I tried making a subfolder for them like with the other custom media folders (I tried several appropriate-sounding names, like Sounds, Sound Effects, and SFX). I tried adding sections to the ini like this:
[Sound Effects]
CuicaMute=CuicaMute.ogg
CuicaOpen=CuicaOpen.ogg
or like this:
[CuicaMute]
File=CuicaMute.ogg
And in all cases, I made a point to try each of the following lines:
ShiftSound(A)=CuicaMute
ShiftSound(A)=CuicaMute.ogg
All of this was to no avail. Nothing I tried got my sound effect to successfully play during the shift.
Does anybody know if it's possible to set up a custom sound effect for a shift? It
looks like there's a system in place, but one thing is for sure: If there is one, it's really hidden!