I doubt Fisher's death impacted the production of the movie in anyway.
You obviously weren't following the news at the time.
When she died it was all over the news how the creative team were all brought together in a huddle sort of like deciding who the new Pope is and waiting for the smoke to go up the chimney. It was in April they made this announcement:
https://arstechnica.com/gaming/2017/04/star-wars-episode-9-carrie-fisher-no-cgi/
Since then we've now been told that she's not going to appear at all, so between April and now it seems like they revised the script yet again.