Zec 12:10 "And I will pour on the house of David and on the inhabitants of Jerusalem the Spirit of grace and supplication; then they will look on Me whom they pierced. Yes, they will mourn for Him as one mourns for his only son, and grieve for Him as one grieves for a firstborn.
This verse is really important, because it agrees with BOTH opposing perspectives presented here - and reconciles them.
In this entire verse, the subject is "the house of David and the inhabitants of Jerusalem". And the verse states BOTH:
1) "Me whom
they pierced".
This clearly states that it was "the house of David and the inhabitants of Jerusalem" who are deemed to have "pierced" Messiah. It squarely lays the blame for His crucifixion at their feet.
2) "And I will pour on [them] the Spirit of grace and supplication; then they will look on Me whom they pierced. Yes, they will mourn for Him as one mourns for his only son, and grieve for Him as one grieves for a firstborn."
This clearly states that those responsible for the crucifixion (or rather a subset of both them and their descendants, represented by them prophetically) will repent and turn to Messiah.
Why is it deemed "antisemitic" or offensive to assert what scripture asserts in many different ways - that it was Israel who are considered responsible for killing Messiah? That simply says that Israel are sinners - and we are all sinners. Is it racist to say that someone is a sinner?
This sin is real - but doesn't ultimately matter if they repent for it and turn to Messiah. And it is prophesied that many will repent and turn to Him, wiping out this sin. Just as all sins are wiped out at repentance.