Collection search

Given the following entries;

Coll #1 EN: Apple (non translated) indexed in ES as:

{
  "_": "Apple",
  "en": "Apple"
}

Coll #2 FR: Légumes (traduit en EN: Vegetables) indexed in ES as:

{
  "_": "Légumes",
  "fr": "Légumes"
  "en": "Vegetables"
}

Elasticsearch query: "collection:Appl" SHOULD: (title[fr]=Appl)boost=100, (title[]=Appl) _boost=50, (title=Appl) _boost=1 (? try in another language)