The json file https://dumps.wikimedia.org/other/contenttranslation/20200214/cx-corpora._2_.html.json.gz is invalid json.
The error is at line 1043441
cx-corpora._2_.html.json 1043439- } 1043440- }, 1043441- , 1043442- { 1043443: "id": "421914/mwAqc", 1043444- "sourceLanguage": "en", 1043445- "targetLanguage": "si", 1043446- "source": {
Note the extra comma.