Here is the MSDS for Tarn-X. I don't see any wax polish in it, but that doesn't mean that it's safe for copper or any other coins. http://www.jelmar.com/msds/SG_MSDS_eng.pdf
I have found the best way to clean silver coins is with my oxy-acetylene cutting torch. To rid the coin of unappealing dirt or patina I simply heat the coin to 1600 degrees F. I'm left a wonderfully clean puddle of molten silver. After cooling down and a quick rinse under water and SHAZAM... u never would have guessed the coin was once dirty.