.json file doesn't change anything, sadly. I tried to change some strings, but as expected nothing changed. I think it's the .dat file where's all this located.
Console is a cure from the most of all bugs. That's why bethesda's TES and Fallout never stuck. Players can just skip or reset quests with console if bugged. I started to look for such a solution here, but sadly found nothing.
But I think, it's strange, that they fixed some quests, which didn't stop your main storyline, but the bug, which doesn't allow you to play at all, they didn't even touch. There's no sence to fix content people can't even see...
Maybe it is the fix, but... I've completed this quest long before I stuck :c
Hope, next patch will fix it.
Somebody know how to open sav.dat file? I saw some people tried to change .json. I think that real save data is in .dat, not in .json.