The element harbingers we heard:
Childe is Hydro.
Scaramouche is anemo.
Arlecchino is pyro.
Columbina is hydro.
Sandrone is >! cryo !<
My prediction:-
Pulcinella looks hydro. People say he will be playable since he's in main trailer so I think he will be first harbinger standard character or 4 star.
Capitano is cryo. People say he will be rimegrass dps since he's master of leyline who suits the most for dendro(knowledge and virtue)+ cryo(preservation). So I too think he's the rimegrass dps.
Pantalone looks geo to me but they can make him dendro as Captain's bis support(I saw people talk about Pantalone being dendro).
Pierro doesn't look playable at all to me at least not in Snezhanaya.
Dottore(I wish they make him playable but..) might get wanderer treatment and comes out Anemo for stellar rimegrass or he might be sandrone's electro bis support (I saw someone pointing out that he have superconduct in his boss mechanic). Although I think he will be killed by The Tsaritsa to show her benevolence.