Since Im the one who initially mentioned the Zechariah passage, Id like to clarify. John says in John 19 that they will look on Him whom they have pierced, but he does not elaborate on them mourning for Him As one would an only son as in Zechariah. Many times Scripture has a double fulfillment. It may be partially fulfilled and then completely fulfilled at a later time. Were people weeping at the cross and mourning greatly. Yes, some were! His followers. But the Zechariah passage seems to indicate vast numbers weeping and in absolute travail maybe literally all Israel at the time! This did not occur initially. When it says they will look on Him they have pierced, it's like you and I . We weren't there but when the revelation of what He did for us is known it brought us to true repentance so we went and mourned over our sin. I think it will be so extremely intense for Israel as they will recognize that Yeshua was bone of their bone, and that He already came to them , and was Whom they had been looking for all along!!!
Other examples would be Isaiah 61:1-3 and Luke 4:18-19. You will note that in the Luke passage Jesus mentions one of the major aspects of His Messiahship as the opening of the eyes of the blind. Notice, it is not in Isaiah, but how many blind did Jesus heal? It was major in His ministry. Could it be because it pointed to man's spiritual blindness as well. Then there is the passage in Matthew, 2"Out of Egypt, have I called my Son. It was first cited in Hisea. Was Jacob(Israel) not sent to Egypt to survive famine but then his descendants forced to leave centuries later because of Pharoah's edict to murder the Hebrews. Once again, Egypt is a haven for a descendant of Jacob, Jesus, tonprotect Him until safe to return to Israel (specifically Nazareth- meaning the branch).
Sometimes the Scripture deals with the natural and the spiritual. If we're born again, we are spiritual but we live in a natural body and a spiritual and natural world.