If a child under age 12 wants to register in proz.com as translator especially for kids contents, Will he be allowed?
Proz.com User Agreement, which we all need to accept in order to register, has the answer to your question under the Eligibility clause:
Our service is available only to individuals who can form legally binding contracts under applicable law. Without limiting the foregoing, our services are not available to minors. If you do not qualify, please do not use ProZ.com.
Hope this helps.