Is the money and the salaries that I obtained as a result of a promotion based on inaccurate documents unlawful, knowing that I have repented and regretted, and my colleague who competed with me for the promotion has forgiven me?

The action you took involved a number of prohibitions and transgressions, including: lying, deception, cheating, submitting a document that has no basis, acquiring money for this job through illicit means, infringing on the rights of others and unlawfully consuming their wealth, persisting in this for a period of time, and paying bribes to obtain certificates for which no academic effort was expended.

What is incumbent upon you now is sincere repentance to Allah.

As for what is incumbent upon you regarding this job and the money earned from it, there is a detailed explanation:

If your skills and competence qualify you for this work, and the forged certificates served no purpose other than giving you precedence over your colleague, then part of your repentance is to ask for his forgiveness, and in this case, the money is lawful for you.

However, if the job was given to you based on these forged certificates and you are not competent for it, then it is incumbent upon you to leave this job, or to disclose the reality to your superior.