**There’s no reliable arrowroot-to-carrageenan substitution ratio for nondairy cheese.** Kappa carrageenan helps cheese set into a firm gel; arrowroot thickens the mixture, so substituting it may give you a soft spread or sauce rather than sliceable cheese. ([Carrageenan properties](https://modernistpantry.com/products/kappa-carrageenan.html), [arrowroot uses](https://www.bobsredmill.com/articles/arrowroot-starch-uses-benefits))

For a firm cheese, use the carrageenan specified or a recipe designed for another setting agent, such as agar.

Could you share the recipe, including how much carrageenan it calls for? That will help determine whether an arrowroot adaptation is practical and how much to try.