Yeah, this event seemed a little lackluster regarding the story aspect.
I feel the Shurima event hasn't progressed; we're still basically in the exact same spot we started this off on. I think the main flaw in the lore here is that we already knew, or could at least deduce, everything that would come from the beginning.
As soon as Azir was revealed, the lore team showed their hand by saying "a long lost emperor and his dominion have resurfaced". There were no surprises, no feeling of progression, because nothing was expanded upon after that first step. They could've gone into what effects this arising had on the rest of the world and developed their characters further, but no, everything has stayed stagnant since.
The videos were cool, but they just felt like a description. I seriously thought they were just build-up for the Shurima event and that we would see what happens afterwards, and needless to say, I was really disappointed where there were only two of them to explain everything that's going on here. All the things in the video just seemed to spontaneously happen without rhyme of or reason as well. It didn't feel like a story or even a single chapter. It all just felt like prologue that should've been used to create hype for the actual event.
Plus, as much as Nasus sounds cool, his storytelling felt...amateurish. If you actually listen to the words themselves separate from the voice and visuals, it's mostly simplistic sentences and repetition. One of the number one rules of storytelling is "show don't tell". The videos were composed of things like "Sivir is stunned!" or "The ancient weapon is a key." which is just boring exposition that, personally, took me out of the moment. It would've been much stronger if they actually showed the impact it had on the characters, whether through visual or audio.
The second half of the second video was the strongest, as it was primarily powerful visuals that got me pumped...just as this event was ending. Shurima rises once more! Too bad we don't see how that matters in anyway.