I find myself in largely in agreement with Joel M. Hoffman's statement on Zechariah 12:10. I think textually it is somewhat ambiguous as it could read at least three different ways. And, this ambiguity is reflected in the variety of renderings found in translations like the JPS Tanakh (1985), The Art Scroll Stone Tanach, KJV 1611, NIV, and Catholic New Jerusalem Bible. One, may wonder why? One may also ask which one is correct if any? Here are but a few comments, educated observations, and opinions on the verse:

12:10.a. אלי “unto me” is often emended to אליו “unto him.” S. R. Driver said that about fifty mss support אליו “unto him” (Driver 266). The context supports אליו. The fifth word in MT beyond this one is עליו “upon him.” John 19:37 and Rev 1:7 read “upon him whom they pierced.” However, Yahweh may be the speaker and may be saying that the people had pierced him metaphorically by their rebellion and ingratitude, or they pierced him when they attacked his representative (perhaps some unidentified martyr).

Smith, Ralph L. Micah–Malachi. Vol. 32. Dallas: Word, Incorporated, 1998. Print. Word Biblical Commentary.

12:10 אֵלַ֖י All the vrss. confirm the 1 sg. sfx. of M. T’s modification of the prep. is consequent on its reverential paraphrase of the verb.אֵ֣ת אֲשֶׁר־ _The variety of the variants illustrates the difficulty felt in translating _the passage, but also precludes evidence for any single alternative Vorlage.דָּקָ֑רוּ On T see Gordon, Hebrew Bible, 347–56.

Gelston, Anthony. The twelve prophets Fascicle 5. Biblia Hebraica Quinta commentary. Deutsche Bibelgesellschaft, Stuttgart, 2010. Electronic Accordance Bible Software.

Notes for 12:10
14 tn Or “dynasty”; Heb “house.”
15 tc Because of the difficulty of the concept of the mortal piercing of God, the subject of this clause, and the shift of pronoun from “me” to “him” in the next, many MSS read אַלֵי אֵת אֲשֶׁר (’ale ’et ’asher, “to the one whom,” a reading followed by NAB, NRSV) rather than the MT’s אֵלַי אֵת אֲשֶׁר (’ela ’et ’asher, “to me whom”). The reasons for such alternatives, however, are clear—they are motivated by scribes who found such statements theologically objectionable—and they should be rejected in favor of the more difficult reading (lectio difficilior) of the MT.tn Or “on me.”
16 tn The Hebrew term בְּכוֹר (békhor, “firstborn”), translated usually in the LXX by πρωτότοκος (prōtotokos), has unmistakable messianic overtones as the use of the Greek term in the NT to describe Jesus makes clear (cf. Col 1:15, 18). Thus, the idea of God being pierced sets the stage for the fatal wounding of Jesus, the Messiah and the Son of God (cf. John 19:37; Rev 1:7). Note that some English translations supply “son” from the context (e.g., NIV, TEV, NLT).

Biblical Studies Press. The NET Bible First Edition Notes. Biblical Studies Press, 2006. Print.