If you double-tap to enter full screen mode, then double-tap again to exit full screen mode, the audio button will appear no matter where you're scrolled in the chapter – which reduces the need to scroll to the top. However, when you open the audio player and press play, it will start at the beginning or (if you've previously started listening in that chapter) wherever the audio left off last time you were listening to that chapter.
To be able to start the audio at a specific verse or paragraph requires the app to know how many seconds into the audio each paragraph starts (for example, paragraph 1 starts at 0 seconds, paragraph 2 starts at 14 seconds, paragraph 3 starts at 27 seconds, etc.). Gathering this data is time-consuming, especially across all of the content the Church provides audio recordings for (if the feature is added in one piece of content, like the English scriptures, users will expect it to work the same everywhere or may be confused about why it only works some places).
I'd recommend sending it as a feature request using "Send Feedback" under Settings in Gospel Library. Common feature requests are reviewed and prioritized against other work.
Samuel Bradshaw • If you desire to serve God, you are called to the work.