@AlexFeuchtwanger -- We don't have editing embed code as something we're prioritizing right now. It's not something we believe most authors need to do very often, and if it is needed it's relatively easy to simply re-add the embed using the new code/link. There are also some technical considerations which we'd have to work through to successfully implement this feature that prevent it from being quick and easy to implement.
If this is something that you'd like to see in a future update I'd encourage you to please add it as an idea on our ideas board along with information about how it will provide value for you and your organization so others can upvote it and weigh in on it's importance.
Owen Evans
Lead Product Engineer | StoryMaps