OK, but with no EDD there is no reason that the character format overrides cannot be removed using the Import Formats function. But as you want to convert the overrides, that would not help you, anyway.
If you can send me a sample document I will have a look at and see if I can create the script for you. It should not be too difficult. The main trick is in finding the sections with the overrides and there are several ways to do this. I don't trust the Find method all too much, so I would move from one paragraph to the next and use GetText to retrieve the sections with character overrides. Ones you have those, it is a walk in the park.
Kind regards
Jang (my mail adress is jang at jang dot nl)