How to fix custom song glitches on emlators.

Test them how? You mean like see if using them can produce glitches in songs, like having it up to the max of 3700 and then adding them into the song data as well?

But no I haven't, all I know is they are more or less basically built into the sound engine and aren't set in the 32 byte instrument data like the other instruments so I doubt they would take any memory from the RAM used for the instruments, to be a cause for the glichiness, but I'm not positive.