henningw left a comment (kamailio/kamailio#4250)
@henningw Correct, only 2xx OK to Generated INVITE will have an ACK in the local request. I tested the 2xx case, @xkaraman tested the non-2xx case, I am not sure if he retested with a 2xx case.
Thanks for the feedback. But it should trigger the event route also for the ACK in the non 200 OK case 3, right?