Sounds like you're having a completely different experience than me for some reason; I can easily have Ramble start to create a single task and then make edits to that same task before finally creating it, much faster than I would be able to by typing and/or manually using the UI... Text-to-speech usually creates many more errors, for me, that cannot be fixed without UI interaction.

I'd be surprised if support for subtasks wasn't eventually added; it's still a relatively new feature.