They use numbers and diacritics to indicate scale degrees! Note value is indicated with a series of circles or partial circles after each number, and some other features of the circles correspond to other features of the note, including dynamics.

Agh why?  Who designed this?  She does not like it?  It can't even simultaneity properly!

Here, let her show you how hers works;

and here goes an explanation and concurrent demonstration of classical music notation!

"- I don't know why you're complaining to me, I didn't design this."

"I need to complain to someone or it'll just sit in my head forever and ever, nagging at me - and you're present, and at least capable of following the discussion.  That said, who did design this?"

"I don't know who... invented... music notation?"

"...Yeah, I figured.  Neither do I.  Still, if music notation had been invented recently enough, maybe I would've had a chance to give them a piece of my mind over this...thisness.  So I had to ask, for some values of 'had'."

"I definitely don't know and also hate whoever invented music notation."

"Well, there's always the option to try doing something bold about it.  Not that I've had much luck trying on my lonesome, so far.

"...I should start making mechanical metronomes."

"Should you now."

"Timekeeping!  It's pretty important!"

"Not that you even have an extant unit of time small enough to meaningfully track beat frequency against, but surely you have some idea of tempo!  Plus, it's useful for individual practice to be able to keep time without having to guess.  Assuming, at least, that someone hasn't beaten me to the punch, here.  I'm torn between my hopes, on that."

"I think usually you just... tap your foot... or something..."

"...As a foot-tapper of some skill myself, it just doesn't work that way until you already have a sense of the flow of the piece.  If you're trying to learn a piece from sheet music?  You want to have timekeeping, otherwise you'll get it wrong."

"Maybe you're not actually very good at foot-tapping."

She stiffens.  "Good sir, I will thank you to not impugn a skill I have trained in since childhood and honed for thousands of cycles, even if I lack the proper accoutrements to prove said skill in an indisputable manner at present."

"That said, I do think I find myself inclined to corner the metronome market.  Thanks!"

"You're welcome..."

"...Excuse my wounded pride; she's just...very invested in maintaining a sense and image of knowing things, at the moment.  Because, despite the fact that I'd really prefer to not be the single repository of so much knowledge that would get lost if I was hit by a cart, well.  I know way too much proveable stuff that only I know, even if some of it's been spread to others.  And I do also think of myself as being a good musician; that didn't help me react with proper equanimity."

"...she?"

"...Are you actually interested in knowing the reason that word choice happened?  It's - rather abstruse.  Or we can chalk it up to inadvertent personification and leave that rabbit hole alone.  ...Damn, you don't have the story that generated that metaphor.  We can leave that entire symphonic production alone?  No, that's not really the right connotation...  We can avoid fighting that demon?  ...Yeah, close enough."

"I mean, if you're otherwise going to, say, buy something, I'd rather talk about that. If you're otherwise going to leave, don't let me stop you. If you want to have a conversation, that's what I'm curious about."

"If I wasn't mostly broke I absolutely would be buying one of your stringed instruments, but unfortunately, I don't have much local money.

"...Should really see if I can find a numismatist, if there's enough coinage worth collecting around here to sustain one.  They'd certainly be interested in trading foreign money from very far away for fungible local currency.

"Still, I suppose I actually do have time and interest in a conversation about the reason I framed my wounded pride as significantly not myself.

"The answer's honestly pretty simple, for all that there's so much complexity behind it - my cohabitation arrangements are between different facets of me, rather than the 'normal' process of soul transfers."

"...huh. Does that... work?"

"There's a lot of potential confounding factors, because the sort of mental structure that enables just sort of stumbling on this trick tends to occur alongside other traits that affect what's mentally fatiguing in the first place, but - yeah?  I certainly haven't randomly passed out or anything like that, yet.  It's actually possible to induce, though I wouldn't necessarily recommend providing such exercises to children that haven't already - demonstrated specific facilities for having imaginary friends, I suppose - though young adults who're already maybe a thousand cycles past puberty, they'd probably be quite fine, and honestly if there's cohabitator matchmaking as a thing, it would be oddly easy to develop reverse-engineering hypothetical people from their partner's desired traits, and those with sufficient...mm, my model of this is surprisingly opaque, but there's relevant traits...

"...If there's anything I really ought to write down stat, it is definitely that sort of thing."

"Well, we do sell notebooks and pens, over there." He gestures.

"Then I think I may end up making a purchase after all."  She grins slightly.