fix: improve search relevance ranking

backend/search/evaluate_relevance.py

@@ -55,6 +55,7 @@ def search(base_url: str, index: str, item: dict, top_k: int) -> list[str]:
                     "multi_match": {
                         "query": item["query"],
                         "fields": [f"document_name_{language}", f"text_{language}"],
+                        "type": "cross_fields",
                     }
                 },
             }