Much as I think item ID needs some extra applications, this isn't one - making it so that 'lost' soulstones can only be identified by a smaller proportion of the player base would logically mean that even fewer get returned to their owners than is currently the case.
For the stones we have now - the system can't or doesn't identify them properly, or they would have the names of past users on them (I've seen several with skills still stored on them marked 'unknown', so clearly those made and not used or only used prior to the code for adding the names was introduced are effectively unidentifiable without some more coding work being done and there seems little priority for such a small impact result).
I think the better solution from now onwards is that they just don't get 'deleted', when a house with soulstones in falls they get shifted to the owning character's (whoever claimed it or last used it) bank. Since that data transfer happens purely on the game server, there's no need for the account to be active to do it. If it also happens that the owning banks is 'full', sadly it's bad luck and the stone gets deleted.