Is it permissible to combine the Maghrib and Isha prayers as a delayed combination (jama' ta'kheer) at home after finishing Italian language classes, due to time constraints and the unavailability of a place to pray at or near the language center?

It is obligatory to perform the prayer at its prescribed time, and it is not permissible to combine it with another prayer except for a legitimate Shar'i excuse. What you have mentioned is not an excuse as long as you can find a place to pray. If you are unable to do so, then you may combine prayers due to need and preoccupation.