Hint Rewrite @sublist_nil' using list_solve: sublist.
Hint Rewrite @app_nil_l : sublist.
Hint Rewrite @Zlength_rev : sublist.
Hint Rewrite @sublist_rejoin' using list_solve : sublist.

Lemma upd_Znth_app1 {A} i l1 l2 (I: 0 <= i < Zlength l1) (v:A):
upd_Znth i (l1++l2) v = upd_Znth i l1 v ++ l2.