It is possible to substitute cream of celery for cream of mushroom in some recipes, but it will likely change the flavor. Cream of celery tends to be slightly milder and sweeter than cream of mushroom, so it may not pair as well with certain flavors or flavors that you may want to include in the recipe. Additionally, cream of mushroom tends to be a bit thicker than cream of celery, so the texture of your dish may also be affected. You may require to adjust cooking times or ingredients if you decide to make this substitution. Ultimately, it is up to you and what flavors or textures you are looking for in the recipe!