I wonder why the ''spirits'' of most previous Runelords are present in the crypt of runes. Afterall, many of them were killed by players (Krune, Karzoug and Alaznist at a minimum. Also Phirandi is in Xin-Edasseril) and would never have been brought there.
It's also hard to explain how Xanderghul would have been able to ''rise'' them considering he would not have access to much material (at best personal objects for the still living Runelords in the crypt).