Here's what I found on McDonald's website:
37 % of their coffee purchases are certified from:
- Rainforest Alliance Certified™
- Fair Trade USA
- UTZ Certified farms
This means 63 % is not certified, and in a company like McDonald's, this is a lot because they purchase in very high quantities.
Furthermore, they say that coffee sold in Europe is 100% certified by one of the three mentioned above. They don't give more details on this.
Like others already said, a company like McDonald's will never be sustainable in the way they work. Such a company will mostly be focused on making money, and not in being sustainable. I don't say companies can never be sustainable, but McDonald's has been the same for decades and I can't imagine they would switch their image from one day to the next.