As a developer, it is not possible to make pull requests to add functionality / fix bugs for the official Roblox Dialogue Editor. Roblox should add the dialogue editor plugin to their Github Studio Tools repository.
As a developer, it is not obvious that there is an official Roblox dialogue editor plugin. Compare the Animation Editor and Dialogue Editor:
There’s no way to tell the dialogue editor is official. It’s not uploaded by Roblox, it doesn’t have an icon, and there’s nothing to indicate it’s official. The dialogue editor is invaluable, but has been tremendously underutilized because it just seems like another user plugin. The plugin should be uploaded to the Roblox account so it’s obvious it’s official, and because if it’s uploaded to a user’s account, staff member or otherwise, that person may not always be there to maintain the plugin.