The patch notes are massive & I tried to avoid spoilers: did they add a merged split screen for combat as well to reduce issues and/or dynamic while travelling around?
No, I don't think they did, at least based on patch notes. Though I didn't see mention of the split-screen delay issue being fixed either. Not a single acknowledgement that it was ever an issue. I mean it was bad enough that they probably didn't want to draw attention to it.
I should add, they did add an option to have players automatically 'listen' to conversations started in split screen, which will be welcome on my end.