Here’s an extract1 from the Oxford Dictionary of English:
Counterpart (noun) 1. a person or thing that corresponds to or has the same function as another person or thing in a different place or situation: the minister held talks with his French counterpart.
As you can see, there is no notion of opposition. “Counterpart” means, more or less “the same, but in a different context”. The proper translation would is thus indeed “homologue” or, in some contexts, “équivalent”.
Homologue (A., —subst.) Personne ou collectivité remplissant un rôle analogue d'une structure à une autre, d'un pays à un autre.
- The other entry is of little interest here.