Timeless jewels already do this correctly - they are not different from other jewels in this respect, and they cannot be. The jewel socket is a passive skill, it's hover element shows the stats that passive grants. This isn't special for jewel sockets, it's just how all passives work - they grant some number of stats (can be zero) and display exactly those stats. Most timeless jewels do not grant any stats directly to their jewel socket (the Templar ones being a notable exception), so the jewel socket their in fundamentally is a passive that does not grant any stats, and thus cannot display any.