“Statues carved in a row”

Overseas ESL students were asked to transform a sentence into passive voice. One gave an unexpected answer, and their teacher consulted with me.

Original: The people of Rapa Nui carved huge statues of heads all in a row.

Expected Answer: Huge statues of heads all in a row were carved by the people of Rapa Nui.

Student Answer: Huge statues of heads were carved by the people of Rapa Nui all in a row.

Main question: Is that the appropriate place for "all in a row"?

The student’s answer struck me as natural enough, but I didn’t know if it was grammatical or idiomatic.

The first question I have is whether "all in a row" is an adverbial phrase modifying "carved", as that’s how the student seemed to interpret it. The teacher’s point of view is that it’s an adjectival phrase modifying "huge statues of heads". In my view, there’s enough ambiguity that both interpretations can be correct. Am I right in my assessment so far?

My mind is bending around whether the statues were physically arranged in a row before being carved or after, but I feel like that might be off-track. At any rate, the final position seems like the only home for "all in a row" in the adverbial sense as "carved all in a row huge statues of heads" doesn’t sound right.

Edit: Actually, "Huge statues of heads were carved all in a row by the people of Rapa Nui" also seems acceptable.

I did find a related StackExchange question: https://ell.stackexchange.com/questions/37601/passive-sentences-placing-an-adverbial-before-or-after-the-agent. There it was concluded that the adverbial "at school" could be placed after the verb or after the agent depending on emphasis:

This homework was done by Vasya at school.

This homework was done at school by Vasya.

The active voice here would be structurally similar to our original, "Vasya did this homework at school." However, "This homework at school was done by Vasya" doesn’t sound right. That’s why I opened this new question, as I don’t think our sentences parallel each other completely.