No once the downld prefs sense a corruption then it is as is. Need to start from scratch in such cases. Going back to an earlier version is one of the ways of corrupting "all" of your incomplete files.
No I'd suggest starting such files from scratch. So it takes a little longer. At least you'll get them. It happens to many of us I assure you. We learn from our mistakes. lol
At least with your new downloads with LW 4.12.6 onward you won't need to stress about resuming.