What is it you did or didn't put on the questionnaire that you're concerned about the CG finding out? I saw you asked a similar question in one of the other sub forums regarding the background check for your security clearance and what that involves. If you have any issues in your background, it's best you address them now, before the background process starts.
If I'm not mistaken, the questionnaires are available to all recruiters once submitted. I'm sure there's some expiration date, but I have no idea what it is