FWIW, my direct experience with most PSR and Tyros models going back to the PSR2000 shows me that whatever the book may say, it can and does happen with OTS and Music Finder. Playlists, being registration based, can obviously do this. I've had to sort it out for students and others many times. Differences between what's in the books and operations in real life are common, not just with Yamaha. Writing an owner's manual is tricky at the best of times - I've done quite a few - and it isn't helped when changes (that may be minor in the minds of the engineer but sometimes with a major effect in real life) are made after the books have been printed and then don't get corrected or an addendum added.
What users should remember is that all of these OTS, Music Finder and Playlist Settings are merely the musical opinions of the person who set them. Most of the 'setters' are good friends of mine and I respect their opinions and settings, though I often disagree with them! And it's sometimes because they do sometimes contain odd key splits.
I've said many times that the 'antidote' to all of this, rather than resorting to resetting, is to create a 'Blank Bank', with just one setting in, that sets the keyboard up exactly as the player wants it. This one setting will then evolve over time as the user finds out more about what they keyboard does and finds out what's best for them. I consider this so important that it's dealt with, along with creating and saving registrations in general, (often in a whole one hour lesson) as soon as the player gets a keyboard in the PSR/PSR-S/PSR-SX and Tyros/Genos classes. And I get all my students to 'roll' their own settings, more involved but ultimately much more fun than using any of the factory settings. OTS and MF quickly become banned in lessons!