Those are apprently for the test flights only and an indigenous engine will take their place on the production AC.
Shows nonetheless that they still lack trust in their own engines, be it cargo planes or fighter planes. The engines are probably currently the single most limitating factor to China's aircraft ambitions.
In another thread i've drawn the line existing IMHO between VLO capabilities and engine development comparing one to sports like high or pole jump and the latter to long distance running.
In one you have a well defined goal to reach and so it doesn't matter how difficult and forbidding it may appear when you begin: as long as you reach it you get points and can compete with others on the same basis, in the other instead also putting on a lot of effort you can only try to partially reduce the existing gap as your competitors are still running along a seemingly infinite line.