I’m also going to use Polylang to translate a site built with Visual Composer in a couple of weeks, so I’m probably going to face the same issues as you, Morten. My work-around would be to either copy/paste the content from the editor in classic mode, or maybe using the Duplicate Post plugin (https://da.www.ads-software.com/plugins/duplicate-post/) to clone my pages and then re-link them afterwards.
I haven’t tried this yet, but it might be a possible work-around for you too… ??
