SIDI BOU SAID, Tunisia ?The insomnia and headaches are constant companions, as is the memory of the bullet-riddled woman he was unable to help. After surviving the attack at Tunisia's Bardo museum, Josep Lluis Cusido has returned to Spain with an unwanted souvenir: fear. Other tourists who survived the attack, like Americans Gillian Grant and Carol Calcagni, recount how the experience has left them tempered with defiance and with an even stronger affinity to the country. Two young Tunisians, radicalized and trained in Libya, shot dead 21 people at the renowned museum before being killed in a shootout with...