NO

Problem:
 f(c()) -> g(c())
 g(c()) -> f(c())
 c() -> d()

Proof:
 Uncurry Processor:
  f4(f(),c()) -> f4(g(),c())
  f4(g(),c()) -> f4(f(),c())
  c() -> d()
  Ground Confluence Processor:
   not UNR by decision procedure.