What would be the syntactic function of Intikas in the following sentence?
They are called Intikas in their language.
It seems to me that in this case the verb call is behaving as a copulative verb, since Intikas can be identified with the subject they and, as a consequence, work as a sort of nominative predicate. But maybe this whole analysis is just misleading.
BillJ left a comment expressing support for your proposed analysis of “Intikas” as a predicative complement.
I would agree.
I don’t think modern linguists would use the term “nominative predicate” because the traditional, prescriptive account of English “case”, according to which the subject of a finite clause is in the “nominative case” and therefore a predicate ought to also be in the nominative case, is not considered to be an accurate model of how English grammar actually works (since speakers actually say things like “It’s me”, where “me” is predicative, but in the form traditionally identified as the “accusative case”).