Well, the Silmarils don't do a whole lot but they're jewels made from what amounts to the second attempt at a ProtoSun and ProtoMoon by the Valar and they're some of the single most important items in Tolkien's writings, up there with the One Ring, so them being representative of having been to the First Age works. I don't know how the Crucible worked or works now but if it functions as a universe-hopping device instead of the actual quest items to hunt I don't see any problem.