I checked in 2023.1 but looks like this is not possible:
Confirming from the documentation, the autocad_layer_desc attribute is only available to use with the Reader: https://docs.safe.com/fme/html/FME-Form-Documentation/FME-ReadersWriters/acad/Feature_Representation.htm
Already have an account? Login
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.