C1-4:    É um pouco a versão de uma espécie de outro lado da noite, a meio caminho entre os devaneios de uma fauna
periférica,  seja de Lisboa, Londres, Dublin ou Faro e Portimão, e a postura circunspecta dos fiéis da casa, que de ela esperam a música geracionista dos 60 ou dos 70.

This is not actually a case of a object complement being a pp. It is a case of a subject complement but the principles are basically the same.
In the finite clause "seja de Lisboa, Dublin. Faro e Portimão" (predicative of the previous noun phrase: fauna periférica), the copulative verb requires a complement, even though the subject is not expressed. The only possible complement is actually a coordination of prepositional phrases. They would be considered adverbials in its pure syntactic form, but despite the fact that they represent a place,  they predicate the subject, providing valency mediated information [ser], and therefore, must be, in fact, considered the subject complement (in a compound unit).