I didn't want to post this as an issue until I/others have done further testing, but the following seems apparent to me:
There appears to be no way to use a custom title solely for PLP; it will always take the object's 'Title', which means courses built with the framework presumably can't have clear, logical 'Titles' such as 'a-01', 'b-10' or 'c-20' if PLP is to be used, because 'a-01' would appear in the PLP drawer.
This is an issue if the author wants to have a unique Title, Display Title and PLP title for one Article or Block.
As previously stated, I didn't want to raise this as an issue yet as I may have missed an available setting in the AT or framework.