Is a person held accountable for his previous statement that Ahl al-Sunnah wal Jama'ah say that the Qur'an is the Word of Allah, and they do not say that it is created, nor that it is not created, after knowing the correct statement that they say it is the Word of Allah and not created?

To transmit knowledge, one must first possess full competence in doing so; otherwise, misunderstandings of the texts of scholars may occur. If you have repented with a complete repentance—regret, abstaining from the sin, and a firm resolve not to return to it—then we hope that Allah will forgive you.