This query did not produce Armenian labels for many items even though they actually exist, only because of the extra space in the language code list. I think the labeling service should be more tolerant, or it should raise an error. Silent ignore is the worst.

SELECT ?item ?itemLabel
WHERE
{
  ?item wdt:P3170 ?heritageId .
  SERVICE wikibase:label { 
    bd:serviceParam wikibase:language "en, hy" .
  }
}