Before revision:  Our results build on a recent work of Chou, Golovnev, Sudan,  and Velusamy who show tight  inapproximability results for some constraint satisfaction problems over arbitrary (finite) alphabets.
After revision:  Our results build on a recent work of Chou, Golovnev, Sudan, and Velusamy who show tight , linear-space inapproximability results for some constraint satisfaction problems over arbitrary (finite) alphabets.