How can one repent for shortcomings or injustices committed against students, and does God accept the repentance of one who resolves to reform in the future despite being unable to be absolved of their worldly rights?

Indeed, Allah is Oft-Forgiving, Most Merciful. He accepts the repentance of His servant as long as the sun has not risen from the West and the soul has not reached the throat. He has promised forgiveness to those who repent and seek His pardon. What you are feeling might be a form of waswasa (whispers from Satan) and misplaced guilt. Even if you have sinned, that does not prevent the acceptance of good deeds. Rather, it is incumbent upon you to offer sincere repentance for any intentional sin. As for unintentional mistakes, Allah overlooks them.

Sincere repentance includes abandoning the sin, regretting it, and resolving not to return to it, as well as restoring rights or seeking forgiveness from those who were wronged. A general seeking of forgiveness from students and administration is sufficient when traveling or at the end of the semester. You are not obliged to quit teaching. Instead, strive to excel in what remains, purify your intention for Allah, treat students with mercy and compassion, and frequently supplicate for forgiveness. Beware of falling into waswasa.