YES

(format LCTRS :logic QF_LIA)
(fun g2 2 :sort (Int Int Int))
(fun triangle2 1 :sort (Int Int))
(fun u_16 1 :sort (Int Int))
(fun u_23 1 :sort (Int Int))

(rule (u_23 w_8_0) w_8_0 :vars ((w_8_0 Int)))
(rule (g2 n_1 s_2) (u_23 (g2 (- n_1 1) (+ n_1 s_2))) :guard (> n_1 0) :vars ((n_1 Int) (s_2 Int)))
(rule (g2 n_3 s_4) s_4 :guard (<= n_3 0) :vars ((n_3 Int) (s_4 Int)))
(rule (u_16 w_6_5) w_6_5 :vars ((w_6_5 Int)))
(rule (triangle2 n_6) (u_16 (g2 n_6 0)) :vars ((n_6 Int)))

Confluent by Newmans Lemma with proof:
terminating and no critical pairs

Elapsed Time:  11.92 ms