Ok, last chapter I didn't catch each Sirens had two quirks each, which add to the mystery.

Sonata got the power to burp gas that she can mold into shapes and eventually transform into life-like puppets that she controls. It need to be fuelled by eating a disturbing amount of food and the puppets existence seem to be limited by either or both a timer and distance to herself.

For her second quirk, she can create portal but she need both a door and to rub the circumference of the portal for it to work. Her chanting sushi-sushi-sushi-suchi while doing it might not be actually necessary because this is Sonata doing it and who knows with the crazy one.

For Adagio we only know one of her quirk so far, she got the power to call an order and people have gmto obey if they hear it. It can be disturbed if people's don't hear it correctly if they talk over her. Her needing a name or the other limits/requirements to the orders she can give are unclear so far. She however loose her voice completely when she use the quirk and we don't know for how long she loose it or an order work.

Same for Aria, she only have shown the one power. It seem to be able to feed kinetic energy into objects to manipulate thems. She seems to favor things with engines because they already provide motions and energy through said engines and plenty of movable parts like doors and panels, hinges probably helping to move things more easily. We haven't seen her use it on her weapons or inarticulated objects so far or those stuck in some places. As a weakness/requirements, I think she need to be touching something to affect it, she cannot do it remotely. I see potential for uses with construction machinery, planes, skateboards, boats, maybe powered armor suits or something like Misaka Mikoto A-A-A suits from A Certain Scientific Railgun.

... I like your choice. They are original and not the ordinary super strength/flight/Lazer beam people seem to automatically think when "super powers" are mentioned, they have weaknesses and requirements for balance, they require both skills and cunning to effectively use and they make the actions and story fun. There seem to be a story o how they got those and the randomness as well has the weaknesses making it seem like they didn't exactly got a choice as to what their quirks would be. Or at least that whoever gave them those can't make perfect quirks.

I wonder if the Sirens know the risks of having multiples quirks?

Do they still have their pastel colored skin from the show? They wouldn't stand out from the crowd with those.

I liked that you gave the Sirens years of experience with martial arts, weapons on top of the skills and nerves to pull the robbery and subsequent events. Am I right to suppose this version if the Sirens have lived for at least a thousand years before they were banished to the Equestria Girls universe? And the sisters seems to be older here because while they had a disguise, the policemen seemed to think they were adults so they can't be teenagers sized (however I'm MHA, size is subjective due to quirks mutating a lot of the population over the centuries).

Meanwhile, Aria Blaze narrowed her eyes. “That's not a camel-toe. That's a camel- canyon .”

“Take it easy, Takeyama...” Death Arms cracked the joints in his neck, clad in a polo shirt and slacks that undermined his otherwise overwrought physique. “Some of us are retired...” An artery in his neck pulsed. “But you don't hear us complaining.”

Ok... so with Death Arms retired, the mention on Nomus and Villains running around by the police captain in the first chapter, I am deducting this is post canon?

And would Death Arms would actually help? Or could? He quit during Japan greatest crisis in shame because he couldn't take the pressure. Shouldn't his license been voided since then?

And since it's seem to be post canon, it couldn't be All for One, Tomura or Doctor Garaki who gave them their Quirks....

“Goddammit! You should have thought this through, Dagi!” Aria Blaze snarled, readying her weapon. “Just how many goddamn fuckers in this country are named ' Shinji' ?!?”

That's actually a twist to Adagio order. Love unpredictable blunders like this.