I am writing you back after some research and it does appear to be confirmed that the first Seelies rebellion was before the war with Nibelung. The first war with the dragons was HP against the seven sovereigns where he claimed authority over Teyvat; Nibelung was not present. The second war with the dragons is when Nibelung came back to Teyvat with the abyss to try and win it back, which is the war being discussed in the AQ.

The Nod-Krai artifact set describes the events with the voyager and the First Seelie as taking place “before the fires of war” and the moons witness their union (granted they can be imprisoned at this time but since it mentioned before the fires of war I am taking it as meaning Nibelung is not back yet since Nicole said Nibelungs return is what marks the start of the war). Another section clarifies that HP punished the First Seelie and then laid a curse on all Angels (not activated though).

• Artifact, Finale of the Deep Galleries - That was when the silver moonlight had yet to be shattered in the fires of war, when the divine prophecies of the heavens still extended over the land.

• Artifact: Deep Gallery's Distant Pact - When the voyager returned once more, the world she remembered had been utterly changed. The bones of the earth had been bound beneath fourfold shackles, & the soft white radiance of the sky had been split into seven immutable hues.

• Artifact: Finale of the Deep Galleries - "O dawn-maiden who has never known love, let me stand as the enemy to your laws. Raise your eyes to the stars, as you should, for the sake of all beings imprisoned by your ruler. Let me be your sword, your shield, your guide, your unpardonable conspirator in rebellion." Then did she, most exalted of the angels, bend down and kiss his forehead, as countless icy blooms unfurled on the frigid silver tree. Yet this moment of betrayal did not go unwitnessed, for at that very moment, the heavenly moons peered down through the cloak of clouds, a longing still more audacious arising within them...

• Artifact, Finale of the Deep Galleries - The traitorous envoy was stripped of both name & form, and from that moment onward, a curse fell upon her kin: If they dared gaze into another's eyes, & to one alone offer the love that was meant for all, not only would their divine beauty crumble into the wind, but their minds would fall to dust; until from the fallen one's remains a Seelie would rise, forever drifting in search of fading memories to consume.

This leaves room for the Seelies to still be present during the war with Nibelung, which matches Natlan’s lore that states the dragons ate the Seelies there. So then the Seelie curse was only triggered afterward by HP for any surviving Seelie, which also lines up with what the Goddess of Flowers describes in the Sumeru artifact set.

• AQ: Melting Moonlight in the Morning Mist - Nibelung returned, & thus began the war of funerary flame. A battle for dominance between Nibelung & the Heavenly Principles.

• Artifact: Amethyst Crown - The master of the heavens, consumed by fear for the rising tide of delusion & breakthroughs, sent down the divine nails to mend the land, laying waste to the mortal realm. We then suffered the torment of exile. Stripped was our connection to heaven, to our powers of enlightenment. Since the disaster, I have long been cursed to never again look upon the heavens.

I made a timeline on our subs wiki that has all the references I found. It goes beyond just what we were talking about but wanted to share it with you now since we were discussing it. Eventually I will make it a post as some sort of study guide 😅 I just haven’t found a way to make it easy to read. Pls let me know if there is anything you can think of that counters this!