Elasticseach highlighting Thai pdf file not work

Question

I index Thai pdf document via ingest-attachment plug-in but when search content in file this display distorted.

This content in pdf:

Mappings:

"attachment": {
                "properties": {
                    "content": {
                        "type": "text",
                        "analyzer": "rebuilt_thai"
                    },
                    "content_length": {
                        "type": "long"
                    },
                    "content_type": {
                        "type": "text",
                        "fields": {
                            "keyword": {
                                "type": "keyword",
                                "ignore_above": 256
                            }
                        }
                    },
                    "date": {
                        "type": "date"
                    }
                }
            }

This search result:

My English isn’t so great but I’ll try.