Nicely explained to the newbie.RD93 is a medium thrust engine and WS10 is a high thrust engine. The huge difference of thrust will lead to the disorder of aerodynamic layout, and finally reduce the combat effectiveness of the fighter.
India once forcibly installed AL31F for MIG27, which finally led to the decline of fighter performance. Britain's replacement of the F4k engine also led to a decline in fighter performance.
So if you want to replace the WS10 with JF17, the aerodynamic layout, inlet and rear fuselage of JF17 will have to be modified. This is tantamount to redesigning a fighter. Moreover, JF17 using WS10 will no longer be a light fighter, but a medium fighter at the same level as F16 and Rafale. This will lead to a significant increase in aircraft manufacturing costs.