Yes, filling in the wrong 12th roll number on your CHET application form can create issues during the application processing and verification stages.

Your 12th roll number is a crucial piece of information used to verify your academic credentials and eligibility for the CHET exam. A mismatch might lead to delays or even rejection of your application.

While you have already mailed NTA, it's good practice to follow up. You can do this by:

• Sending a reminder email referencing your previous email and application details.
• Trying the NTA helpline number  if available, to explain your situation and seek guidance.
  
  If the email and helpline don't provide a solution, you can try contacting NTA through their official social media channels (Twitter, Facebook) if they have them. Briefly explain your situation and request their help in rectifying the error.
  
  This is not an ideal solution, but if you don't hear back from NTA and the deadline for fresh applications hasn't passed, consider filling out a new application form only if allowed with the correct roll number.
  
  I hope it helps!