Chaol is healed, even the scar on his face that Aelin gave him in Crown of Midnight is healed. Chapter 64: The cost Yrene paid is that her and Chaol now share a life-bond. Chaol can use his legs and walk when her magic is at its fullest, when she is weak he will still need his chair.

Is Chaol crippled?

Queen of Shadows

He is stopped by the Thirteen, and is almost killed himself. Chaol later participates in a battle against the King and is grievously injured, resulting in his legs being paralysed.

Is Chaol healed in Tower of Dawn?

She chooses to forgive Adarlan for what its soldiers did to her family and her people, and then she treats Chaol. To be fully healed Chaol must forgive himself for his failed relationships with Aelin and Nesryn, and his failure to protect his soldiers and Dorian when they needed him most.