We are left with following problem, upon which TcT provides the
certificate YES(?,O(n^1)).

Strict Trs:
  { h(f(x), y) -> f(g(x, y))
  , g(x, y) -> h(x, y) }
Obligation:
  innermost runtime complexity
Answer:
  YES(?,O(n^1))

The problem is match-bounded by 2. The enriched problem is
compatible with the following automaton.
{ h_0(2, 2) -> 1
, h_1(2, 2) -> 1
, h_2(2, 2) -> 3
, f_0(2) -> 2
, f_1(3) -> 1
, f_1(3) -> 3
, g_0(2, 2) -> 1
, g_1(2, 2) -> 3 }

Hurray, we answered YES(?,O(n^1))