There is no official Global ROM for the R11st. Oppo never released one. The company segments its devices strictly by region.
The R11st is nearly identical to the R11s in terms of physical build. : 6.01-inch AMOLED with an 18:9 aspect ratio. oppo r11st global rom exclusive
If you are not comfortable with command-line interfaces and risking a $200 paperweight, do not attempt this. There is no official Global ROM for the R11st