The html of the edit dialog is dynamically added to the DOM whenever you open the edit dialog for a given node. It is then removed from the DOM when the dialog closes. I don't know anything about how angular works to suggest why it isn't working here. Have you added anything to your oneditprepare function to tell angular to do anything with the newly added content?
By 'support' we mean that as the main contributors to the node-red code we don't know the answers to your questions and it isn't something we choose to spend our time trying to figure out for you. Sorry.