I can only speak for myself, but I would guess “no performing experience” is very relevant here. Beyond the “beginner level” of learning to physically operate the instrument, any sort of “performance” involves a feedback loop of imagining what sound you want to produce, and making corrections to your actions playing the instrument (either on-the-fly in live performance, or through a lot of hard thinking and experimenting in the rehearsal room) to produce what you imagined.
IMO it doesn’t seem a big step beyond that to imagine something and write it down reasonably accurately, without continual checking through computer playback. In fact I sometimes switch off “play notes as you enter them” because the “random noises” when jumping around between different instruments in the score are more of a distraction than a help.
One of my favorite quotes (from Kodaly) is about exactly this duality: “The goal of music education is to teach you how to see with your ears, and hear with your eyes”.
The developers claim to have found a logical error which manifests itself in ways that don’t fit any obvious pattern that the user would be likely to find, and fixed it.
From my experience of software development, the only way to find out of that is a “complete” solution to the problem is to wait and see what happens after you fixed it. But Occam’s razor often applies, and “randomly occurring” problems tend to have one root cause (which can take a long time to track down!), not several.