What would be a more academically acceptable name for a cluster of four courses?
Such mini-programs are sometimes called certificates.

Certificate programs are sometimes meant to be completed stand-alone, often by students who are not enrolled in a degree program but are looking for continuing education in a particular area, e.g. to help with their career.  However, they can also be taken on top of a bachelor's or graduate degree. They often consist of just a few courses.

As an example, you can read about my own institution's Certificate in Music Technology, which consists of 12 credit hours.