YES

1 decompositions
 #1 -----------
   1: F(G(x1,A(),B())) -> x1
   2: G(F(H(C(),D())),x2,x3) -> H(K1(x2),K2(x3))
   3: K1(A()) -> C()
   4: K2(B()) -> D()

@Knuth and Bendix' criterion
--- R
   1: F(G(x1,A(),B())) -> x1
   2: G(F(H(C(),D())),x2,x3) -> H(K1(x2),K2(x3))
   3: K1(A()) -> C()
   4: K2(B()) -> D()

--- S
   1: F(G(x1,A(),B())) -> x1
   2: G(F(H(C(),D())),x2,x3) -> H(K1(x2),K2(x3))
   3: K1(A()) -> C()
   4: K2(B()) -> D()