The Heichal does not say who breaks the flask!
Radak: "Ish" is omitted. Similarly, "Im Yacharosh ba'Bekarim" (Amos 6:12) omits the one who plows.
What is the comparison to breaking the flask?
Malbim: This is unlike breaking clay in the potter's hand; then, he fixes it and makes another Kli. When a finished earthenware Kli is broken, it cannot be fixed.
What is "Leherafe"?
Radak: It is to be cured, as if there is an Aleph at the end.
What cannot be cured?
Rashi: The nation. However, I will make the city like a furnace, and purify it in the future.
Radak: [The nation and] the city. This is an anthropomorphism, like "va'Yrapei Es Mizbach Hashem he'Harus" (Melachim I, 18:30).
What is the significance of burial in Tofes?
Radak: It was their place of idolatry (7:31).
Malbim: It is to make the place Tamei, just like they were Metamei it.