So I went over in my head what could be cut from Stormblood while staying narratively sound.
Kugane:
When looking for Gosetsu and Yugiri have us talk to a seisekgumi with Alphinaud's drawing, immediately getting the scene with Gosetsu at the barracks.
This cuts out meeting namazu and meeting Soraban. This can happen as we will be going to the Kojin of the blue settlement later and namazu aren't needed for plot.
Ruby Sea
Have a confederate accept money we obtain from Lolorito and we sail to Isari never meeting vice captain until after Yotsuyu. Also have the captain explain they have fallen on hard times lately and have Alisae or Lyse put two and two together sooner. Have Soroban at the entrance to Tamimizu who takes you to the elder.
Yanxia
Have Gosetsu immediately take you to the hideout rather than going to the village 1st. Have Isse show up when you go there with Yugiri and he finds out we are with the resistance. No target practice with Yugiri just straight to Castrum to get the uniforms.
Azem Steppe
After Bardum's mettle go straight to the Nardum. Have Lyse + Hein talk with Mol, same with Gosetsu and us.
Yea ik blasphemy to cut little sun and Sadu but they are not needed for main plot outside we'll help you fight which the rules of the steppe and their own pride get them to. Sadu can have small introduction when asked to dispel barrier so when she comes back for 4.4 stuff she still fits.
Yanxia's part 2
Hien's epiphany to destroy the dam, just have him say it as Alphinaud explains the plan.
That is just a small amount I can think of but cutting them would undermine a lot of character moments some of these character drop off hard as well not getting another chance to be involved in msq, lost of world building also happens when you go about cutting too much.
It is a fine line and I highly doubt the devs will go back over again to do more pruning until it drastically needs to be done which is yet to be the case as they have not stated they will be doing so within their current schedule.