2nd part
To put it into perspective, the Sirens have dimensional travel capabilities, among other insane technological feats. They make the "Fog of War" fleet from Arpeggio of Blue Steel look like child’s play. If you really break down their abilities and what they’re capable of, it’s honestly ridiculous. That's why whenever I see modern ships taking them down in the story, I can't help but laugh my ass off, because when you actually understand the Sirens’ true capabilities, it just seems completely absurd.
But honestly, it’s totally fine that the Sirens are portrayed this way. Azur Lane’s lore is ridiculously complicated, and the game’s Quality of Life (QoL) mechanics don't make it any easier to dive deep into the story. To make things even more frustrating, most of the crucial lore is locked behind limited-time events rather than main story chapters, which makes it super easy for people to miss out on important details or just ignore them altogether. So yeah, I don't blame people for overlooking the deeper aspects of the Sirens’ lore.
Anyway, good luck with writing your series, bruh! I'm just giving you some insight into just how insanely powerful the Sirens actually are. Hope it helps!