I would suggest that you name the files by an ID and index them in an array along side the data you would like to know about them; title, length, artist. Many of the libraries for the DFPlayer do not use the filename at all. They go by the order they are stored on the SD card.
I am wondering if is a way I can do the same but for the dfplayer, that will be amazing. Is there any way I can hack the module to use sdfat with it?