While developing T194387, I found one obscure way to restore the draft with the wrong version of Content Translation.
- Start fresh translation in production. I used srwiki to translate en:Last_Glacial_Maximum to Serbian.
- Once the translation is started, Content Translation will start with version=1 in the URL. Change to version=2 to translate using CX2.
- Translate one paragraph, save and return to the dashboard.
- If you returned using "All translations" button, you will get URL in the format of https://sr.wikipedia.org/wiki/Special:ContentTranslation. Append ?page=$page_name&from=$source_lang&to=$target_lang to the URL and follow the new URL. Content Translation will start with the default version, which is CX1 and the loading will break
In the case of my example ?page=$page_name&from=$source_lang&to=$target_lang is "?page=Last_Glacial_Maximum&from=en&to=sr".