Visual Composer is listed in Known Issues: https://qtranslatexteam.wordpress.com/known-issues/.
Since you did not use it before, you would not lose much with not using it, would you? While this may be a comforting thought for your personally, but in general, the issue stays open and troublesome.
Yes, I was told that there is a ticket at Visual Composer support to enable compatibility with qTranslate-X, like they previously did with original qTranslate. Please, contact them with this issue. The more people complain, the quicker they will update it. You may also mention to them, that the qTranslate Team is ready to cooperate with them, if they have some questions.
Thanks. Unfortunately my existing translated pages stopped working. Will have a look at the other post.
Unfortunately my existing translated pages
Then this is not exactly a Visual Composer compatibility topic. How exactly they stopped working? Front-end? Admin-side? Screenshots may help? Is this related to q-X or more related to the theme? Have you tried the latest version from GitHub?