Firstly, I know an idea was implemented to sort starred songs so thank you for listening to that and implementing!
I do think it would be incredibly usefule, though, to be able to manually sort the order of songs in your 'Starred' / 'Hearted' library.
It sounds silly but there are certain songs that I love to listen to in a certain order or I have found different versions of songs that I prefer. Rather than dilute the top of my starred songs with a different version of an older song, I would much prefer to be able to drag and drop further down in my list of songs (exactly like you can with the song queue).
I know I'm not the only one would apprceiate this addition.