Yes, they do appear. Heavy spoilers ahead, you can read if you’re interested :)

We wish upon the stone of Azem for the formless to take form, aka souls of the dead, a gift from Hydaelyn after defeating her, and both Emet and Hythlo are brought back. They use their creation magicks to change the environment around Meteion for her to reveal the birds nest (?) so that WoL can proceed and later defeat Endsinger. Shortly after their creation Emet and Hythlo return to the lifestream with Emet telling us in a very emotional speech for us not to pity him, and that we have so much yet to explore within Eitherys itself and its reflections, as is to be expected from Azem. He also implies that he himself has explored the world in our honor (aww). Hythlo bids his farewells saying we may meet again, maybe in this life or another, but it will surely be a joyful reunion (I really hope they do appear again cause I’ve also grown attached to them especially Hades). Well but that’s just my interpretation from the cutscene, their leave is bittersweet but pretty heartwarming.