No, the chinese knew the debt was unsustainable, that was kind of the point. The problem is that the rest of the world caught on that China was loading up poorer countries with debts that they had little chance of repaying, and has started to exert pressure to stop it. It seems to be working.

Belt and Road is a scheme to gain control of trade routes between China and Europe. The goal for China is to hold those debts and have some measure of influence in the countries they have built transortation infrastructure in. They aren't trying to make money by running a lending business.