What is the ruling on the financial compensation and certificates I received from training courses in governmental and private companies, knowing that my enrollment in these courses was through 'wasta' (favoritism) and they were mixed-gender? And is it permissible for me to benefit from these certificates in my resume?

Mediation or intercession is the exertion of influence with people in authority to fulfill people's needs. The basic ruling on it is permissibility; indeed, it is among the matters encouraged by the Lawgiver. This is based on the Prophet's (peace be upon him) saying: "Intercede, and you will be rewarded, and Allah will decree through the tongue of His Messenger whatever He wills." It becomes forbidden if it leads to the affirmation of falsehood or the nullification of truth. Not all mediation is forbidden; some of it is lawful, and some is unlawful. There is no harm in benefiting from the reward or certificates for the two courses as long as you attended them.