I chose not to fix the problem, instead I just redid all the work. I had all the assets still and it was a question of reimporting, replacing and relighting, had to redo some blueprints tho, but since It’s a simple environment and not a game it was fine.
I have not found any fixes. You might get lucky and have some backup .umaps work in the autosave directory, but for me they were [redacted] as well. You could have some luck enabling .ue4 to make it able to read .json files through some .cfg editing
sorry.
STAFF EDIT: Profanity removed. Please refrain from swearing on AnswerHub.