Hi,
1. Ideally Accounts department is responsible for drafting & updating Form -16 for the employees.
2. Role of HR is to provide inputs to Accounts team, unless the HR is sound enough in this process.
3. HR has to incorporate & verify the details mentioned by the employees & made the employees understand all the compliances related to FORM 16. Form 16Will be disbursed only after Apr 30.

Hope this will help you in some extent to understand basically the Form 16 procedure.