Unfortunately we haven’t gotten pressure from our non-subscriber licensees to complete this system. Most big companies either opt to swap in their own audio system and/or audio localization system. Epic internally isn’t yet approaching a time when we would need these features for our own games.
That said I totally agree with your sentiment and see this as a pretty crucial part of the engine.
As for the SoundCues what are you using to play them? Blueprints, code, something else?
Also I haven’t tried it yet, but you may be able to multiselect all your SoundWaves / DialogueWaves and use the Property Matrix in the right-click menu of the content browser. This would allow you to inspect, edit, and sort properties within any uobject. All you might have to do is pin the Subtitle property as a column to quickly get the information you desire.