"has been making changes" is correct and usable in written English.
You can use it to describe someone or something that has been making gradual modifications or improvements over time. For example: "The company has been making changes to its workplace policies to ensure a more inclusive environment."
But he has been making changes lately.
To right the ship, Disney has been making changes.
Executives say the timing is coincidental, but Bloomberg TV has been making changes of its own.
As well as trying to keep clients and bracing itself for lawsuits, Marsh has been making changes.
Fatigue is the club's greatest opponent as they challenge on three fronts and Benitez has been making changes match-to-match to cope with it.
But recently the company has been making changes to its service, and some of those changes seem to be responses to what competitors are doing.
However a recent review of the progress made in integrating CSR issues into the business school curriculum concludes that although progress has been made, changes are predominantly cosmetic (Baden & Higgs 2015).
Other lenders have been making changes to criteria, with Barclays increasing the rent needed to cover repayments to 135% in December.
"We've been making changes for the last four or five years because students started expressing a greater interest," said Ted Mayer, executive director of university dining services.
Robert S. Mueller, director of the F.B.I., said today that the bureau had been making changes to carry out the inspector general's recommendations, to retrain employees on document handling and to make records management a priority.
Airlines have been making changes in their frequent flier programs, increasingly giving their best rewards not just to passengers who fly the most but who also pay the highest fares.
