Thanks for taking the time to make that tutorial, really appreciate your effort on this 
That’s the same method I used to split the tracks but,
If you double tap the remaining audio in each track the audio editor should appear
The audio editor shows that the entire audio file is still there.
The beginning hasn’t really been removed.
The split and erase just changes where the audio events start from.
It’s not a problem with short audio files but with 2 hr sessions it would save a lot of space if the split / erase could be applied to the original file