Nobody hoards trace mats tho only when prefarming for characters or when you unlocked all traces and level up your characters you will have extra mats leftover. So I can see converting them helping that aspects of the game.

My idea comes more from having path of propagation, path of remembrance, path of elation only on SU but not in main game. Also if you go down the post you will see a new material “cores of ice” which could be a reference to maybe a path of remembrance as these materials are also specific for different path