Another update. Today, after disabling threaded audio, I was able to play through the entire port of Al Emmo on iOS, without it silently crashing even once. I think this is the first time I've ever been able to accomplish this! (Though, I swear it has crashed in the past on Android with threaded audio disabled).
Either way, the "silent crash" glitch looks like it's almost certainly narrowed down to threaded audio.