Cambridge IELTS 10 example essay. Adj or Adv after a verb?

Here is a sentence from the example essay of Cambridge IELTS 10, Test 1:

"This kind but firm approach will achieve more than harsh punishment, which might entail many negative consequences unintended by the parents."

My question is that why a adjective "unintended" is used after a verb "entail"?

"Unintended" is a past participle that introduces a passive, reduced relative clause

"many negative consequences unintended by the parents." = many negative consequences that were unintended by the parents."

Compare the use of the continuous participle that introduces an active reduced relative clause

"many negative consequences surprising the parents." =many negative consequences that surprised the parents."

This kind but firm approach will achieve more than harsh punishment, which might entail many negative consequences [unintended by the parents].

"Unintended" is not an adjective here, but a past participle verb heading the bracketed past-participial clause modifying "consequences".

Past-participials (and gerund-participials) as modifiers in noun phrase structure are semantically similar to relative clauses: cf. "negative consequences which are unintended by the parents", but we don't analyse them as relative clauses since there is no possibility of them containing a relative phrase (cf. *"consequences which unintended by the parents").

Past-participial modifiers are 'bare' passives, as evident from the admissibility of a by phrase.