Every character ever is a trope if we try hard enough, the bigger thing to me is how each trope is used and what it does for the story. Alisaie for the first 3 or so years of development I feel only really does anything because she's Alphinaud's sister, if Alphinaud didn't have a sister she wouldn't have much purpose to be here and at that point it just feels like additional muscle. Her more unique traits come into full effect by ShB, but HW > SB is just whatever most the time and Coil is her only relevant moment(s) but she shares the big end with Alphinaud anyway. That's why I feel Alisaie is more superfluous for the first half of her time being in the main cast. The Ga bu stuff is cute and that comes back later, but it takes years for that to truly go anywhere and it feels like just a center point of Alisaie's character growth is just delayed until then.
For all of Alphinaud's shit, he does actually contribute something as being the main political voice for the protagonist's side while also being the main idealistic voice in the group. Alphinaud's voice is important as the WoL is basically voiceless in a political heavy series of conflicts. Alphinaud carrying the idealistic core of the story, choosing to talk first ,and avoid just using murder to solve problems is what keeps the Scions on the heroic path where everyone else fails. Alisaie brings something else later, and the two combined (with bits from the other Scions) I feel ultimately form as a sort of intended collective voice for the WoL's position against the antagonists.
Alphinaud pushed his way forward because he ultimately had to given the situation as he think he is one of the last remaining Scions, but even to this day I can still see how much his failures eat at him as he outright comments on it multiple times especially in Shadowbringers. I don't know if I'd call it subtle, but I do genuinely feel Alphinaud is a different person from HW on and I don't find his writing inconsistent. Alisaie's character moments being there more, I feel that's more because Alisaie is much more expressive and emotionally driven while Alphinaud (attempts) keeps an air of professionalism so his changes are more subdued and buried. It is most shown in how they show grief when they acknowledge Louisaix's death, Alisaie cries and Alphinaud attempts to shows resolve in the face of his demise.
Now this is another "I've been playing since 2013, so my experience is different" point, but playing ARR/HW again on an alt made me realize something. This story does not flow as good if you literally blitz it as you can do today, every patch story ending is supposed to be followed by an implied passage of time which really doesn't work when you can go from 2.1-2.3 in an afternoon. That's why everyone goes "Alright we need to stop doing stuff because reasons..." and then you get another quest 5 seconds later if you play today. So for example in 2.55's ending to 3.0's start, their is an implied point where Alphinaud is effectively moping around waiting for asylum (and you can talk to him as an npc during this time) to Ishgard. So for me Alphinaud's change isn't that sudden as I waited for that moment and that wait to some extent is canon within the story.
I think a good amount of our perceptions is due to the fact that how we've experienced the story is different. I think the story was better written for how I viewed it (over time, patches, discussion etc) then how you did as that was obviously the intention for the player base to experience it that way, and the relative binge watching we have today is a consequence of the MSQ's design. Not that all of this makes Alphinaud a perfect character as he is incredibly obnoxious in ARR and if his growth isn't enough then ARR is even worse, but I see Alphinaud's growth more fondly because I dealt with shitlord redditor for 2 years straight every 3-4 months, and got to see him steadily grow and change for the following 6 years after he fucked everything. So as I stated earlier, for me he stands out because he's the only character who's constantly growing in big and small ways due to him being the defacto protagonist that is voiced.