That’s wrong friend, Its not me who designed the circuit, but still I can say that the R9 is for limiting the current flowing towards LED indicator only. It has nothing to do with the entire circuit. reducing the value may burn off the LED with the 30V input and nothing else.
Learn to respect a circuit design as I do, which has been designed by some one who knows every details of it. Every single component is designed based on the minor details.
It is not like you can reduce the design voltage input and expect the circuit to work simply by reducing the value of a resistance.