So she's going to learn All Soul's Rest first, mostly because with the burden that she bears, with the guilt of a hundred lives lost in her care, she can't not.
And while this will take a little while for her to learn, it won't be that long, (Hi Babe!), and she's going to start to mash up her three separate styles of performance into something very, very new
Siren Song is a very direct effect, it changes the world physically, and you can feel it with your 5 normal senses. It affects what already is. Performance magic creates from thin air, and can bolster, but only for as long as one is performing.
Using all three, Pinya could summon a Primal. Without the use of Aether and without the worry of tempering because although its 'real' its also her creation.
And so, the thing about is a belief is you just have to get people open to the idea. Possibly, very possibly, with enough teamwork, they could work together to create a space completely in dependant from the Arcana.
Now, I'm not savvy enough with the background of the game to know these answers, but you see, Pinya's echo? It's a lie detector. It's not worked so great inside liminal, because reality, 'truth', is subjective to these arcana
Anyway I like to plot game-breaking mechanics a little bit, and frankly she's totally seen people fretting about whether or not the game actually does pause time or not in their native universes
Now see, this is why I'm trying to get pinya invested in the actual plot of the Game, because she hates hates hates not knowing what's going on. She's an intelligence agent, and she can't staaaand it
So obviously Pinya's next logical thought is "how much do I have to accelerate on the spot to get enough of gh momentum to clip out of bounds" ie, how much faith can she collect for a small song-powered black hole.
So the way I'm looking at it is like, three components. Performance sets the precedence, the outcome for the spell. Bardic is all the maths and science and strings, Siren Song becomes the faith, the channelling of power