Lastwall has a problem.
Well, really, it has several problems. Its spymaster and most powerful wizard is dead and in Hell, many of its covert operations throughout Avistan have correspondingly been burned, and its attempt at alliance with Avistan’s most powerful wizard has collapsed in spectacular fashion, leaving it with a supply route to the Worldwound that it’s not going to be able to defend, and slightly less of Ustalav ruled by undead but more of it ruled by Cheliax, and, frankly, egg on its face in the sight of the international community, which is not something any of Lastwall’s decision-makers are personally inclined to track but is, in fact, strategically relevant.
Most of the strategic cost of Jean Riudaure’s death was presumed lost within minutes of his death, and from a strictly utilitarian point of view, saving him from Hell’s wrath is just not worth the enormous cost of recovering a sold soul, which might, otherwise spent, increase their chances of victory for everyone, but there were other considerations besides his own suffering which led Lastwall to provide Felandriel Morgethai with a Wish diamond and ask her to wrench him from Hell’s grasp. Riudaure was the most well-known soul-sold defector in the world, with a bounty on his soul equal to that on Queen Galfrey’s, and he joined Lastwall’s service with their explicit promise of protection from Hell. To leave him there, no matter the cost, would not only ensure Lastwall never received another high-level defector from Cheliax, it would also strain their ability to call themselves Lawful Good.
—except that, for Jean Riudaure, even a Wish will not be enough. One can revive most soul-sold people that way, even when no lesser force will suffice, but only because a ninth-circle caster can typically beat the Will save of an ordinary contract devil. Riuduare is not most people, and his new owner has a substantially better Will save than an ordinary contract devil.
At this point, even they are inclined to give up. Spending vast resources on the successful rescue of an ally would be one thing. Spending those resources, when all they can bring to bear will not even be enough, would be simply foolish, and Iomedae is not the goddess of Stupid Good.