All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is not permissible to forge a certificate to prove experience, as this leads to many forbidden matters like the following:
1. Deliberate lying: the Prophet said: "Lying leads to vice (wickedness, evil-doing), and vice leads to Hellfire, and a man continues to tell lies till he is written before Allaah, as a liar."
2. Deceiving: The Prophet said: "He who deceives is not of us." [Muslim]
3. Giving false testimony: There is a severe threat about giving false testimony, a threat that makes a person refrain and stay away from it. The Prophet said: "Shall I not inform you about the greatest of the major sins, they said: "Indeed, O Prophet of Allaah []! He said: "To associate partners with Allaah, and to be undutiful to one’s parents." He was lying down and then he sat up [to show the importance of what he was going to say next], and said: "And false testimony…" The Prophet kept repeating it [false testimony] until we wished that he kept quiet (because they didn't like to see him angry).'' [Al-Bukhari and Muslim].
Allaah knows best.