So with the game prioritizing your avatar as the main speaker thing, I don’t think it’s actually fixed. I’ve seen two cases where a companion was selected over the avatar for a very important cutscene.
From what I can tell it seems half-fixed. eg. Ethel will still default to talking to Lae'zel in Act 1 in the dialogue that occurs prior to her offering her +stat hair, but other instances it's been working properly, like when you rescue Rolan in the shadow-cursed lands.
I'll be on the lookout for other instances.
Also been looking for that new Shadowheart banter in act 2, I've just walked into Moonrise (map is cleared apart from the Reithwin Mausoleum/Gauntlet of Shar) and haven't encountered a single instance. Wondering if that isn't working as intended either.